Section XXXIII. 2. 9. In this disease the actions of these vessels

producing ulcers on the throat and skin are imperfect imitations of those

producing chanker, or gonorrhoea; since the matter produced by them is not

infectious, while the imitative actions in the hydrophobia appear to be

perfect resemblances, as they produce a material equally infectious with

the original one, which induced them.

The contagion from the bite of a mad dog differs from other contagious

materials, from its being communicable from other animals to mankind, and

from many animals to each other; the phenomena attending the hydrophobia

are in some degree explicable on the foregoing theory. The infectious

matter does not appear to enter the circulation, as it cannot be traced

along the course of the lymphatics from the wound, nor is there any

swelling of the lymphatic glands, nor does any fever attend, as occurs in

the small-pox, and in many other contagious diseases; yet by some unknown

process the disease is communicated from the wound to the throat, and that

many months after the injury, so as to produce pain and hydrophobia, with a

secretion of infectious saliva of the same kind, as that of the mad dog,

which inflicted the wound.

This subject is very intricate.--It would appear, that by certain morbid

actions of the salivary glands of the mad dog, a peculiar kind of saliva is

produced; which being instilled into a wound of another animal stimulates

the cutaneous or mucous glands into morbid actions, but which are

ineffectual in respect to the production of a similar contagious material;

but the salivary glands by irritative sympathy are thrown into similar

action, and produce an infectious saliva similar to that instilled into the

wound.

Though in many contagious fevers a material similar to that which produced

the disease, is thus generated by imitation; yet there are other infectious

materials, which do not thus propagate themselves, but which seem to act

like slow poisons. Of this kind was the contagious matter, which produced

the jail-fever at the assizes at Oxford about a century ago. Which, though

fatal to so many, was not communicated to their nurses or attendants. In

these cases, the imitations of the fine vessels, as above described, appear

to be imperfect, and do not therefore produce a matter similar to that,

which stimulates them; in this circumstance resembling the venereal matter

in ulcers of the throat or skin, according to the curious discovery of Mr.

Hunter above related, who found, by repeated inoculations, that it would

not infect. Hunter on Venereal Disease, Part vi. ch. 1.

Another example of morbid imitation is in the production of a great

quantity of contagious matter, as in the inoculated small-pox, from a small

quantity of it inserted into the arm, and probably diffused in the blood.

These particles of contagious matter stimulate the extremities of the fine

arteries of the skin, and cause them to imitate some properties of those

particles of contagious matter, so as to produce a thousandfold of a

similar material. See Sect. XXXIII. 2. 6. Other instances are mentioned in

the Section on Generation, which shew the probability that the extremities

of the seminal glands may imitate certain ideas of the mind, or actions of

the organs of sense, and thus occasion the male or female sex of the

embryon. See Sect. XXXIX. 6.

4. We come now to those imitations, which are not attended with sensation.

Of these are all the irritative ideas already explained, as when the retina

of the eye imitates by its action or configuration the tree or the bench,

which I shun in walking past without attending to them. Other examples of

these irritative imitations are daily observable in common life; thus one

yawning person shall set a whole company a yawning; and some have acquired

winking of the eyes or impediments of speech by imitating their companions

without being conscious of it.

5. Besides the three species of imitations above described there may be

some associate motions, which may imitate each other in the kind as well as

in the quantity of their action; but it is difficult to distinguish them

from the associations of motions treated of in Section XXXV. Where the

actions of other persons are imitated there can be no doubt, or where we

imitate a preconceived idea by exertion of our locomotive muscles, as in

painting a dragon; all these imitations may aptly be referred to the

sources above described of the propensity to activity, and the facility of

repetition; at the same time I do not affirm, that all those other apparent

sensitive and irritative imitations may not be resolvable into associations

of a peculiar kind, in which certain distant parts of similar irritability

or sensibility, and which have habitually acted together, may affect each

other exactly with the same kinds of motion; as many parts are known to

sympathise in the quantity of their motions. And that therefore they may be

ultimately resolvable into associations of action, as described in Sect.

XXXV.

* * * * *

SECT. XXIII.

OF THE CIRCULATORY SYSTEM.

I. _The heart and arteries have no antagonist muscles. Veins absorb the

blood, propel it forwards, and distend the heart; contraction of the

heart distends the arteries. Vena portarum._ II. _Glands which take

their fluids from the blood. With long necks, with short necks._ III.

_Absorbent system._ IV. _Heat given out from glandular secretions.

Blood changes colour in the lungs and in the glands and capillaries._

V. _Blood is absorbed by veins, as chyle by lacteal vessels, otherwise

they could not join their streams._ VI. _Two kinds of stimulus,

agreeable and disagreeable. Glandular appetency. Glands originally

possessed sensation._

I. We now step forwards to illustrate some of the phenomena of diseases,

and to trace out their most efficacious methods of cure; and shall commence

this subject with a short description of the circulatory system.

As the nerves, whose extremities form our various organs of sense and

muscles, are all joined, or communicate, by means of the brain, for the

convenience perhaps of the distribution of a subtile ethereal fluid for the

purpose of motion; so all those vessels of the body, which carry the

grosser fluids for the purposes of nutrition, communicate with each other

by the heart.

The heart and arteries are hollow muscles, and are therefore indued with

power of contraction in consequence of stimulus, like all other muscular

fibres; but, as they have no antagonist muscles, the cavities of the

vessels, which they form, would remain for ever closed, after they have

contracted themselves, unless some extraneous power be applied to again

distend them. This extraneous power in respect to the heart is the current

of blood, which is perpetually absorbed by the veins from the various

glands and capillaries, and pushed into the heart by a power probably very

similar to that, which raises the sap in vegetables in the spring, which,

according to Dr. Hale's experiment on the stump of a vine, exerted a force

equal to a column of water above twenty feet high. This force of the

current of blood in the veins is partly produced by their absorbent power,

exerted at the beginning of every fine ramification; which may be conceived

to be a mouth absorbing blood, as the mouths of the lacteals and lymphatics

absorb chyle and lymph. And partly by their intermitted compression by the

pulsations of their generally concomitant arteries; by which the blood is

perpetually propelled towards the heart, as the valves in many veins, and

the absorbent mouths in them all, will not suffer it to return.

The blood, thus forcibly injected into the chambers of the heart, distends

this combination of hollow muscles; till by the stimulus of distention they

contract themselves; and, pushing forwards the blood into the arteries,

exert sufficient force to overcome in less than a second of time the vis

inertiæ, and perhaps some elasticity, of the very extensive ramifications

of the two great systems of the aortal and pulmonary arteries. The power

necessary to do this in so short a time must be considerable, and has been

variously estimated by different physiologists.

The muscular coats of the arterial system are then brought into action by

the stimulus of distention, and propel the blood to the mouths, or through

the convolutions, which precede the secretory apertures of the various

glands and capillaries.

In the vessels of the liver there is no intervention of the heart; but the

vena portarum, which does the office of an artery, is distended by the

blood poured into it from the mesenteric veins, and is by this distention

stimulated to contract itself, and propel the blood to the mouths of the

numerous glands, which compose that viscus.

II. The glandular system of vessels may be divided into those, which take

some fluid from the circulation; and those, which give something to it.

Those, which take their fluid from the circulation are the various glands,

by which the tears, bile, urine, perspiration, and many other secretions

are produced; these glands probably consist of a mouth to select, a belly

to digest, and an excretory aperture to emit their appropriated fluids; the

blood is conveyed by the power of the heart and arteries to the mouths of

these glands, it is there taken up by the living power of the gland, and

carried forwards to its belly, and excretory aperture, where a part is

separated, and the remainder absorbed by the veins for further purposes.

Some of these glands are furnished with long convoluted necks or tubes, as

the seminal ones, which are curiously seen when injected with quicksilver.

Others seem to consist of shorter tubes, as that great congeries of glands,

which constitute the liver, and those of the kidneys. Some have their

excretory apertures opening into reservoirs, as the urinary and

gall-bladders. And others on the external body, as those which secrete the

tears, and perspirable matter.

Another great system of glands, which have very short necks, are the

capillary vessels; by which the insensible perspiration is secreted on the

skin; and the mucus of various consistences, which lubricates the

interstices of the cellular membrane, of the muscular fibres, and of all

the larger cavities of the body. From the want of a long convolution of

vessels some have doubted, whether these capillaries should be considered

as glands, and have been led to conclude, that the perspirable matter

rather exuded than was secreted. But the fluid of perspiration is not

simple water, though that part of it, which exhales into the air may be

such; for there is another part of it, which in a state of health is

absorbed again; but which, when the absorbents are diseased, remains on the

surface of the skin, in the form of scurf, or indurated mucus. Another

thing, which shews their similitude to other glands, is their sensibility

to certain affections of the mind; as is seen in the deeper colour of the

skin in the blush of shame, or the greater paleness of it from fear.

III. Another series of glandular vessels is called the absorbent system;

these open their mouths into all the cavities, and upon all those surfaces

of the body, where the excretory apertures of the other glands pour out

their fluids. The mouths of the absorbent system drink up a part or the

whole of these fluids, and carry them forwards by their living power to

their respective glands, which are called conglobate glands. There these

fluids undergo some change, before they pass on into the circulation; but

if they are very acrid, the conglobate gland swells, and sometimes

suppurates, as in inoculation of the small-pox, in the plague, and in

venereal absorptions; at other times the fluid may perhaps continue there,

till it undergoes some chemical change, that renders it less noxious; or,

what is more likely, till it is regurgitated by the retrograde motion of

the gland in spontaneous sweats or diarrhoeas, as disagreeing food is

vomited from the stomach.

IV. As all the fluids, that pass through these glands, and capillary

vessels, undergo a chemical change, acquiring new combinations, the matter

of heat is at the same time given out; this is apparent, since whatever

increases insensible perspiration, increases the heat of the skin; and when

the action of these vessels is much increased but for a moment, as in

blushing, a vivid heat on the skin is the immediate consequence. So when

great bilious secretions, or those of any other gland, are produced, heat

is generated in the part in proportion to the quantity of the secretion.

The heat produced on the skin by blushing may be thought by some too sudden

to be pronounced a chemical effect, as the fermentations or new

combinations taking place in a fluid is in general a slower process. Yet

are there many chemical mixtures in which heat is given out as

instantaneously; as in solutions of metals in acids, or in mixtures of

essential oils and acids, as of oil of cloves and acid of nitre. So the

bruised parts of an unripe apple become almost instantaneously sweet; and

if the chemico-animal process of digestion be stopped for but a moment, as

by fear, or even by voluntary eructation, a great quantity of air is

generated, by the fermentation, which instantly succeeds the stop of

digestion. By the experiments of Dr. Hales it appears, that an apple during

fermentation gave up above six hundred times its bulk of air; and the

materials in the stomach are such, and in such a situation, as immediately

to run into fermentation, when digestion is impeded.

As the blood passes through the small vessels of the lungs, which connect

the pulmonary artery and vein, it undergoes a change of colour from a dark

to a light red; which may be termed a chemical change, as it is known to be

effected by an admixture of oxygene, or vital air; which, according to a

discovery of Dr. Priestley, passes through the moist membranes, which

constitute the sides of these vessels. As the blood passes through the

capillary vessels, and glands, which connect the aorta and its various

branches with their correspondent veins in the extremities of the body, it

again loses the bright red colour, and undergoes some new combinations in

the glands or capillaries, in which the matter of heat is given out from

the secreted fluids. This process therefore, as well as the process of

respiration, has some analogy to combustion, as the vital air or oxygene

seems to become united to some inflammable base, and the matter of heat

escapes from the new acid, which is thus produced.

V. After the blood has passed these glands and capillaries, and parted with

whatever they chose to take from it, the remainder is received by the

veins, which are a set of blood-absorbing vessels in general corresponding

with the ramifications of the arterial system. At the extremity of the fine

convolutions of the glands the arterial force ceases; this in respect to

the capillary vessels, which unite the extremities of the arteries with the

commencement of the veins, is evident to the eye, on viewing the tail of a

tadpole by means of a solar, or even by a common microscope, for globules

of blood are seen to endeavour to pass, and to return again and again,

before they become absorbed by the mouths of the veins; which returning of

these globules evinces, that the arterial force behind them has ceased. The

veins are furnished with valves like the lymphatic absorbents; and the

great trunks of the veins, and of the lacteals and lymphatics, join

together before the ingress of their fluids into the left chamber of the

heart; both which evince, that the blood in the veins, and the lymph and

chyle in the lacteals and lymphatics, are carried on by a similar force;

otherwise the stream, which was propelled with a less power, could not

enter the vessels, which contained the stream propelled with a greater

power. From whence it appears, that the veins are a system of vessels

absorbing blood, as the lacteals and lymphatics are a system of vessels

absorbing chyle and lymph. See Sect. XXVII. 1.

VI. The movements of their adapted fluids in the various vessels of the

body are carried forwards by the actions of those vessels in consequence of

two kinds of stimulus, one of which may be compared to a pleasurable

sensation or desire inducing the vessel to seize, and, as it were, to

swallow the particles thus selected from the blood; as is done by the

mouths of the various glands, veins, and other absorbents, which may be

called glandular appetency. The other kind of stimulus may be compared to

disagreeable sensation, or aversion, as when the heart has received the

blood, and is stimulated by it to push it forwards into the arteries; the

same again stimulates the arteries to contract, and carry forwards the

blood to their extremities, the glands and capillaries. Thus the mesenteric

veins absorb the blood from the intestines by glandular appetency, and

carry it forward to the vena portarum; which acting as an artery contracts

itself by disagreeable stimulus, and pushes it to its ramified extremities,

the various glands, which constitute the liver.

It seems probable, that at the beginning of the formation of these vessels

in the embryon, an agreeable sensation was in reality felt by the glands

during secretion, as is now felt in the act of swallowing palatable food;

and that a disagreeable sensation was originally felt by the heart from the

distention occasioned by the blood, or by its chemical stimulus; but that

by habit these are all become irritative motions; that is, such motions as

do not affect the whole system, except when the vessels are diseased by

inflammation.

* * * * *

SECT. XXIV.

OF THE SECRETIONS OF SALIVA, AND OF TEARS, AND OF THE LACRYMAL SACK.

I. _Secretion of saliva increased by mercury in the blood._ 1. _By the

food in the mouth. Dryness of the mouth not from a deficiency of

saliva._ 2. _By Sensitive ideas._ 3. _By volition._ 4. _By distasteful

substances. It is secreted in a dilute and saline state. It then

becomes more viscid._ 5. _By ideas of distasteful substances._ 6. _By

nausea._ 7. _By aversion._ 8. _By catenation with stimulating

substances in the ear._ II. 1. _Secretion of tears less in sleep. From

stimulation of their excretory duct._ 2. _Lacrymal sack is a gland._ 3.

_Its uses._ 4. _Tears are secreted, when the nasal duct is stimulated._

5. _Or when it is excited by sensation._ 6. _Or by volition._ 7. _The

lacrymal sack can regurgitate its contents into the eye._ 8. _More

tears are secreted by association with the irritation of the nasal duct

of the lacrymal sack, than the puncta lacrymalia can imbibe. Of the

gout in the liver and stomach._

I. The salival glands drink up a certain fluid from the circumfluent blood,

and pour it into the mouth. They are sometimes stimulated into action by

the blood, that surrounds their origin, or by some part of that

heterogeneous fluid: for when mercurial salts, or oxydes, are mixed with

the blood, they stimulate these glands into unnatural exertions; and then

an unusual quantity of saliva is separated.

1. As the saliva secreted by these glands is most wanted during the

mastication of our food, it happens, when the terminations of their ducts

in the mouth are stimulated into action, the salival glands themselves are

brought into increased action at the same time by association, and separate

a greater quantity of their juices from the blood; in the same manner as

tears are produced in greater abundance during the stimulus of the vapour

of onions, or of any other acrid material in the eye.

The saliva is thus naturally poured into the mouth only during the stimulus

of our food in mastication; for when there is too great an exhalation of

the mucilaginous secretion from the membranes, which line the mouth, or too

great an absorption of it, the mouth becomes dry, though there is no

deficiency in the quantity of saliva; as in those who sleep with their

mouths open, and in some fevers.

2. Though during the mastication of our natural food the salival glands are

excited into action by the stimulus on their excretory ducts, and a due

quantity of saliva is separated from the blood, and poured into the mouth;

yet as this mastication of our food is always attended with a degree of

pleasure; and that pleasurable sensation is also connected with our ideas

of certain kinds of aliment; it follows, that when these ideas are

reproduced, the pleasurable sensation arises along with them, and the

salival glands are excited into action, and fill the mouth with saliva from

this sensitive association, as is frequently seen in dogs, who slaver at

the sight of food.

3. We have also a voluntary power over the action of these salival glands,

for we can at any time produce a flow of saliva into our mouth, and spit

out, or swallow it at will.

4. If any very acrid material be held in the mouth, as the root of

pyrethrum, or the leaves of tobacco, the salival glands are stimulated into

stronger action than is natural, and thence secrete a much larger quantity

of saliva; which is at the same time more viscid than in its natural state;

because the lymphatics, that open their mouths into the ducts of the

salival glands, and on the membranes, which line the mouth, are likewise

stimulated into stronger action, and absorb the more liquid parts of the

saliva with greater avidity; and the remainder is left both in greater

quantity and more viscid.

The increased absorption in the mouth by some stimulating substances, which

are called astringents, as crab juice, is evident from the instant dryness

produced in the mouth by a small quantity of them.

As the extremities of the glands are of exquisite tenuity, as appears by

their difficulty of injection, it was necessary for them to secrete their

fluids in a very dilute state; and, probably for the purpose of stimulating

them into action, a quantity of neutral salt is likewise secreted or formed

by the gland. This aqueous and saline part of all secreted fluids is again

reabsorbed into the habit. More than half of some secreted fluids is thus

imbibed from the reservoirs, into which they are poured; as in the urinary

bladder much more than half of what is secreted by the kidneys becomes

reabsorbed by the lymphatics, which are thickly dispersed around the neck

of the bladder. This seems to be the purpose of the urinary bladders of

fish, as otherwise such a receptacle for the urine could have been of no

use to an animal immersed in water.

5. The idea of substances disagreeably acrid will also produce a quantity

of saliva in the mouth; as when we smell very putrid vapours, we are

induced to spit out our saliva, as if something disagreeable was actually

upon our palates.

6. When disagreeable food in the stomach produces nausea, a flow of saliva

is excited in the mouth by association; as efforts to vomit are frequently

produced by disagreeable drugs in the mouth by the same kind of

association.

7. A preternatural flow of saliva is likewise sometimes occasioned by a

disease of the voluntary power; for if we think about our saliva, and

determine not to swallow it, or not to spit it out, an exertion is produced

by the will, and more saliva is secreted against our wish; that is, by our

aversion, which bears the same analogy to desire, as pain does to pleasure;

as they are only modifications of the same disposition of the sensorium.

See Class IV. 3. 2. 1.

8. The quantity of saliva may also be increased beyond what is natural, by

the catenation of the motions of these glands with other motions, or

sensations, as by an extraneous body in the ear; of which I have known an

instance; or by the application of stizolobium, siliqua hirsuta, cowhage,

to the seat of the parotis, as some writers have affirmed.

II. 1. The lacrymal gland drinks up a certain fluid from the circumfluent

blood, and pours it on the ball of the eye, on the upper part of the

external corner of the eyelids. Though it may perhaps be stimulated into

the performance of its natural action by the blood, which surrounds its

origin, or by some part of that heterogeneous fluid; yet as the tears

secreted by this gland are more wanted at some times than at others, its

secretion is variable, like that of the saliva above mentioned, and is

chiefly produced when its excretory duct is stimulated; for in our common

sleep there seems to be little or no secretion of tears; though they are

occasionally produced by our sensations in dreams.

Thus when any extraneous material on the eye-ball, or the dryness of the

external covering of it, or the coldness of the air, or the acrimony of

some vapours, as of onions, stimulates the excretory duct of the lacrymal

gland, it discharges its contents upon the ball; a quicker secretion takes

place in the gland, and abundant tears succeed, to moisten, clean, and

lubricate the eye. These by frequent nictitation are diffused over the

whole ball, and as the external angle of the eye in winking is closed

sooner than the internal angle, the tears are gradually driven forwards,

and downwards from the lacrymal gland to the puncta lacrymalia.

2. The lacrymal sack, with its puncta lacrymalia, and its nasal duct, is a

complete gland; and is singular in this respect, that it neither derives

its fluid from, nor disgorges it into the circulation. The simplicity of

the structure of this gland, and both the extremities of it being on the

surface of the body, makes it well worthy our minuter observation; as the

actions of more intricate and concealed glands may be better understood

from their analogy to this.

3. This simple gland consists of two absorbing mouths, a belly, and an

excretory duct. As the tears are brought to the internal angle of the eye,

these two mouths drink them up, being stimulated into action by this fluid,

which they absorb. The belly of the gland, or lacrymal sack, is thus

filled, in which the saline part of the tears is absorbed, and when the

other end of the gland, or nasal duct, is stimulated by the dryness, or

pained by the coldness of the air, or affected by any acrimonious dust or

vapour in the nostrils, it is excited into action together with the sack,

and the tears are disgorged upon the membrane, which lines the nostrils;

where they serve a second purpose to moisten, clean, and lubricate, the

organ of smell.

4. When the nasal duct of this gland is stimulated by any very acrid

material, as the powder of tobacco, or volatile spirits, it not only

disgorges the contents of its belly or receptacle (the lacrymal sack), and

absorbs hastily all the fluid, that is ready for it in the corner of the

eye; but by the association of its motions with those of the lacrymal

gland, it excites that also into increased action, and a large flow of

tears is poured into the eye.

5. This nasal duct is likewise excited into strong action by sensitive

ideas, as in grief, or joy, and then also by its associations with the

lacrymal gland it produces a great flow of tears without any external

stimulus; as is more fully explained in Sect. XVI. 8. on Instinct.

6. There are some, famous in the arts of exciting compassion, who are said

to have acquired a voluntary power of producing a flow of tears in the eye;

which, from what has been said in the section on Instinct above mentioned,

I should suspect, is performed by acquiring a voluntary power over the

action of this nasal duct.

7. There is another circumstance well worthy our attention, that when by

any accident this nasal duct is obstructed, the lacrymal sack, which is the

belly or receptacle of this gland, by slight pressure of the finger is

enabled to disgorge its contents again into the eye; perhaps the bile in

the same manner, when the biliary ducts are obstructed, is returned into

the blood by the vessels which secrete it?

8. A very important though minute occurrence must here be observed, that

though the lacrymal gland is only excited into action, when we weep at a

distressful tale, by its association with this nasal duct, as is more fully

explained in Sect. XVI. 8; yet the quantity of tears secreted at once is

more than the puncta lacrymalia can readily absorb; which shews _that the

motions occasioned by associations are frequently more energetic than the

original motions, by which they were occasioned_. Which we shall have

occasion to mention hereafter, to illustrate, why pains frequently exist in

a part distant from the cause of them, as in the other end of the urethra,

when a stone stimulates the neck of the bladder. And why inflammations

frequently arise in parts distant from their cause, as the gutta rosea of

drinking people, from an inflamed liver.

The inflammation of a part is generally preceded by a torpor or quiescence

of it; if this exists in any large congeries of glands, as in the liver, or

any membranous part, as the stomach, pain is produced and chilliness in

consequence of the torpor of the vessels. In this situation sometimes an

inflammation of the parts succeeds the torpor; at other times a distant

more sensible part becomes inflamed; whose actions have previously been

associated with it; and the torpor of the first part ceases. This I

apprehend happens, when the gout of the foot succeeds a pain of the biliary

duct, or of the stomach. Lastly, it sometimes happens, that the pain of

torpor exists without any consequent inflammation of the affected part, or

of any distant part associated with it, as in the membranes about the

temple and eye-brows in hemicrania, and in those pains, which occasion

convulsions; if this happens to gouty people, when it affects the liver, I

suppose epileptic fits are produced; and, when it affects the stomach,

death is the consequence. In these cases the pulse is weak, and the

extremities cold, and such medicines as stimulate the quiescent parts into

action, or which induce inflammation in them, or in any distant part, which

is associated with them, cures the present pain of torpor, and saves the

patient.

I have twice seen a gouty inflammation of the liver, attended with

jaundice; the patients after a few days were both of them affected with

cold fits, like ague-fits, and their feet became affected with gout, and

the inflammation of their livers ceased. It is probable, that the uneasy

sensations about the stomach, and indigestion, which precedes gouty

paroxysms, are generally owing to torpor or slight inflammation of the

liver, and biliary ducts; but where great pain with continued sickness,

with feeble pulse, and sensation of cold, affect the stomach in patients

debilitated by the gout, that it is a torpor of the stomach itself, and

destroys the patient from the great connexion of that viscus with the vital

organs. See Sect. XXV. 17.

* * * * *

SECT. XXV.

OF THE STOMACH AND INTESTINES.

1. _Of swallowing our food. Ruminating animals._ 2. _Action of the

stomach._ 3. _Action of the intestines. Irritative motions connected

with these._ 4. _Effects of repletion._ 5. _Stronger action of the

stomach and intestines from more stimulating food._ 6. _Their action

inverted by still greater stimuli. Or by disgustful ideas. Or by

volition._ 7. _Other glands strengthen or invert their motions by

sympathy._ 8. _Vomiting performed by intervals._ 9. _Inversion of the

cutaneous absorbents._ 10. _Increased secretion of bile and pancreatic

juice._ 11. _Inversion of the lacteals._ 12. _And of the bile-ducts._

13. _Case of a cholera._ 14. _Further account of the inversion of

lacteals._ 15. _Iliac passions. Valve of the colon._ 16. _Cure of the

iliac passion._ 17. _Pain of gall-stone distinguished from pain of the

stomach. Gout of the stomach from torpor, from inflammation.

Intermitting pulse owing to indigestion. To overdose of foxglove. Weak

pulse from emetics. Death from a blow on the stomach. From gout of the

stomach._

1. The throat, stomach, and intestines, may be considered as one great

gland; which like the lacrymal sack above mentioned, neither begins nor

ends in the circulation. Though the act of masticating our aliment belongs

to the sensitive class of motions, for the pleasure of its taste induces

the muscles of the jaw into action; yet the deglutition of it when

masticated is generally, if not always, an irritative motion, occasioned by

the application of the food already masticated to the origin of the

pharinx; in the same manner as we often swallow our spittle without

attending to it.

The ruminating class of animals have the power to invert the motion of

their gullet, and of their first stomach, from the stimulus of this

aliment, when it is a little further prepared; as is their daily practice

in chewing the cud; and appears to the eye of any one, who attends to them,

whilst they are employed in this second mastication of their food.

2. When our natural aliment arrives into the stomach, this organ is

simulated into its proper vermicular action; which beginning at the upper

orifice of it, and terminating at the lower one, gradually mixes together

and pushes forwards the digesting materials into the intestine beneath it.

At the same time the glands, that supply the gastric juices, which are

necessary to promote the chemical part of the process of digestion, are

stimulated to discharge their contained fluids, and to separate a further

supply from the blood-vessels: and the lacteals or lymphatics, which open

their mouths into the stomach, are stimulated into action, and take up some

part of the digesting materials.

3. The remainder of these digesting materials is carried forwards into the

upper intestines, and stimulates them into their peristaltic motion similar

to that of the stomach; which continues gradually to mix the changing

materials, and pass them along through the valve of the colon to the

excretory end of this great gland, the sphincter ani.

The digesting materials produce a flow of bile, and of pancreatic juice, as

they pass along the duodenum, by stimulating the excretory ducts of the

liver and pancreas, which terminate in that intestine: and other branches

of the absorbent or lymphatic system, called lacteals, are excited to drink

up, as it passes, those parts of the digesting materials, that are proper

for their purpose, by its stimulus on their mouths.

4. When the stomach and intestines are thus filled with their proper food,

not only the motions of the gastric glands, the pancreas, liver, and

lacteal vessels, are excited into action; but at the same time the whole

tribe of irritative motions are exerted with greater energy, a greater

degree of warmth, colour, plumpness, and moisture, is given to the skin

from the increased action of those glands called capillary vessels;

pleasurable sensation is excited, the voluntary motions are less easily

exerted, and at length suspended; and sleep succeeds, unless it be

prevented by the stimulus of surrounding objects, or by voluntary exertion,

or by an acquired habit, which was originally produced by one or other of

these circumstances, as is explained in Sect. XXI. on Drunkenness.

At this time also, as the blood-vessels become replete with chyle, more

urine is separated into the bladder, and less of it is reabsorbed; more

mucus poured into the cellular membranes, and less of it reabsorbed; the

pulse becomes fuller, and softer, and in general quicker. The reason why

less urine and cellular mucus is absorbed after a full meal with sufficient

drink is owing to the blood-vessels being fuller: hence one means to

promote absorption is to decrease the resistance by emptying the vessels by

venesection. From this decreased absorption the urine becomes pale as well

as copious, and the skin appears plump as well as florid.

By daily repetition of these movements they all become connected together,

and make a diurnal circle of irritative action, and if one of this chain be

disturbed, the whole is liable to be put into disorder. See Sect. XX. on

Vertigo.

5. When the stomach and intestines receive a quantity of food, whose

stimulus is greater than usual, all their motions, and those of the glands

and lymphatics, are stimulated into stronger action than usual, and perform

their offices with greater vigour and in less time: such are the effects of

certain quantities of spice or of vinous spirit.

6. But if the quantity or duration of these stimuli are still further

increased, the stomach and throat are stimulated into a motion, whose

direction is contrary to the natural one above described; and they

regurgitate the materials, which they contain, instead of carrying them

forwards. This retrograde motion of the stomach may be compared to the

stretchings of wearied limbs the contrary way, and is well elucidated by

the following experiment. Look earnestly for a minute or two on an area an

inch square of pink silk, placed in a strong light, the eye becomes

fatigued, the colour becomes faint, and at length vanishes, for the

fatigued eye can no longer be stimulated into direct motions; then on

closing the eye a green spectrum will appear in it, which is a colour

directly contrary to pink, and which will appear and disappear repeatedly,

like the efforts in vomiting. See Section XXIX. 11.

Hence all those drugs, which by their bitter or astringent stimulus

increase the action of the stomach, as camomile and white vitriol, if their

quantity is increased above a certain dose become emetics.

These inverted motions of the stomach and throat are generally produced

from the stimulus of unnatural food, and are attended with the sensation of

nausea or sickness: but as this sensation is again connected with an idea

of the distasteful food, which induced it; so an idea of nauseous food will

also sometimes excite the action of nausea; and that give rise by

association to the inversion of the motions of the stomach and throat. As

some, who have had horse-flesh or dogs-flesh given them for beef or mutton,

are said to have vomited many hours afterwards, when they have been told of

the imposition.

I have been told of a person, who had gained a voluntary command over these

inverted motions of the stomach and throat, and supported himself by

exhibiting this curiosity to the public. At these exhibitions he swallowed

a pint of red rough gooseberries, and a pint of white smooth ones, brought

them up in small parcels into his mouth, and restored them separately to

the spectators, who called for red or white as they pleased, till the whole

were redelivered.

7. At the same time that these motions of the stomach and throat are

stimulated into inversion, some of the other irritative motions, that had

acquired more immediate connexions with the stomach, as those of the

gastric glands, are excited into stronger action by this association; and

some other of these motions, which are more easily excited, as those of the

gastric lymphatics, are inverted by their association with the retrograde

motions of the stomach, and regurgitate their contents, and thus a greater

quantity of mucus, and of lymph, or chyle, is poured into the stomach, and

thrown up along with its contents.

8. These inversions of the motion of the stomach in vomiting are performed

by intervals, for the same reason that many other motions are reciprocally

exerted and relaxed; for during the time of exertion the stimulus, or

sensation, which caused this exertion, is not perceived; but begins to be

perceived again, as soon as the exertion ceases, and is some time in again

producing its effect. As explained in Sect. XXXIV. on Volition, where it is

shewn, that the contractions of the fibres, and the sensation of pain,

which occasioned that exertion, cannot exist at the same time. The exertion

ceases from another cause also, which is the exhaustion of the sensorial

power of the part, and these two causes frequently operate together.

9. At the times of these inverted efforts of the stomach not only the

lymphatics, which open their mouths into the stomach, but those of the skin

also, are for a time inverted; for sweats are sometimes pushed out during

the efforts of vomiting without an increase of heat.

10. But if by a greater stimulus the motions of the stomach are inverted

still more violently or more permanently, the duodenum has its peristaltic

motions inverted at the same time by their association with those of the

stomach; and the bile and pancreatic juice, which it contains, are by the

inverted motions brought up into the stomach, and discharged along with its

contents; while a greater quantity of bile and pancreatic juice is poured

into this intestine; as the glands, that secrete them, are by their

association with the motions of the intestine excited into stronger action

than usual.

11. The other intestines are by association excited into more powerful

action, while the lymphatics, that open their mouths into them, suffer an

inversion of their motions corresponding with the lymphatics of the

stomach, and duodenum; which with a part of the abundant secretion of bile

is carried downwards, and contributes both to stimulate the bowels, and to

increase the quantity of the evacuations. This inversion of the motion of

the lymphatics appears from the quantity of chyle, which comes away by

stools; which is otherwise absorbed as soon as produced, and by the immense

quantity of thin fluid, which is evacuated along with it.

12. But if the stimulus, which inverts the stomach, be still more powerful,

or more permanent, it sometimes happens, that the motions of the biliary

glands, and of their excretory ducts, are at the same time inverted, and

regurgitate their contained bile into the blood-vessels, as appears by the

yellow colour of the skin, and of the urine; and it is probable the

pancreatic secretion may suffer an inversion at the same time, though we

have yet no mark by which this can be ascertained.

13. Mr. ---- eat two putrid pigeons out of a cold pigeon-pye, and drank

about a pint of beer and ale along with them, and immediately rode about

five miles. He was then seized with vomiting, which was after a few periods

succeeded by purging; these continued alternately for two hours; and the

purging continued by intervals for six or eight hours longer. During this

time he could not force himself to drink more than one pint in the whole;

this great inability to drink was owing to the nausea, or inverted motions

of the stomach, which the voluntary exertion of swallowing could seldom and

with difficulty overcome; yet he discharged in the whole at least six

quarts; whence came this quantity of liquid? First, the contents of the

stomach were emitted, then of the duodenum, gall-bladder, and pancreas, by

vomiting. After this the contents of the lower bowels, then the chyle, that

was in the lacteal vessels, and in the receptacle of chyle, was

regurgitated into the intestines by a retrograde motion of these vessels.

And afterwards the mucus deposited in the cellular membrane, and on the

surface of all the other membranes, seems to have been absorbed; and with

the fluid absorbed from the air to have been carried up their respective

lymphatic branches by the increased energy of their natural motions, and

down the visceral lymphatics, or lacteals, by the inversion of their

motions.

14. It may be difficult to invent experiments to demonstrate the truth of

this inversion of some branches of the absorbent system, and increased

absorption of others, but the analogy of these vessels to the intestinal

canal, and the symptoms of many diseases, render this opinion more probable

than many other received opinions of the animal oeconomy.

In the above instance, after the yellow excrement was voided, the fluid

ceased to have any smell, and appeared like curdled milk, and then a

thinner fluid, and some mucus, were evacuated; did not these seem to

partake of the chyle, of the mucous fluid from all the cells of the body,

and lastly, of the atmospheric moisture? All these facts may be easily

observed by any one, who takes a brisk purge.

15. Where the stimulus on the stomach, or on some other part of the

intestinal canal, is still more permanent, not only the lacteal vessels,

but the whole canal itself, becomes inverted from its associations: this is

the iliac passion, in which all the fluids mentioned above are thrown up by

the mouth. At this time the valve in the colon, from the inverted motions

of that bowel, and the inverted action of this living valve, does not

prevent the regurgitation of its contents.

The structure of this valve may be represented by a flexile leathern pipe

standing up from the bottom of a vessel of water: its sides collapse by the

pressure of the ambient fluid, as a small part of that fluid passes through

it; but if it has a living power, and by its inverted action keeps itself

open, it becomes like a rigid pipe, and will admit the whole liquid to

pass. See Sect. XXIX. 2. 5.

In this case the patient is averse to drink, from the constant inversion of

the motions of the stomach, and yet many quarts are daily ejected from the

stomach, which at length smell of excrement, and at last seem to be only a

thin mucilaginous or aqueous liquor.

From whence is it possible, that this great quantity of fluid for many

successive days can be supplied, after the cells of the body have given up

their fluids, but from the atmosphere? When the cutaneous branch of

absorbents acts with unnatural strength, it is probable the intestinal

branch has its motions inverted, and thus a fluid is supplied without

entering the arterial system. Could oiling or painting the skin give a

check to this disease?

So when the stomach has its motions inverted, the lymphatics of the

stomach, which are most strictly associated with it, invert their motions

at the same time. But the more distant branches of lymphatics, which are

less strictly associated with it, act with increased energy; as the

cutaneous lymphatics in the cholera, or iliac passion, above described. And

other irritative motions become decreased, as the pulsations of the

arteries, from the extra-derivation or exhaustion of the sensorial power.

Sometimes when stronger vomiting takes place the more distant branches of

the lymphatic system invert their motions with those of the stomach, and

loose stools are produced, and cold sweats.

So when the lacteals have their motions inverted, as during the operation

of strong purges, the urinary and cutaneous absorbents have their motions

increased to supply the want of fluid in the blood, as in great thirst; but

after a meal with sufficient potation the urine is pale, that is, the

urinary absorbents act weakly, no supply of water being wanted for the

blood. And when the intestinal absorbents act too violently, as when too

great quantities of fluid have been drank, the urinary absorbents invert

their motions to carry off the superfluity, which is a new circumstance of

association, and a temporary diabetes supervenes.

16. I have had the opportunity of seeing four patients in the iliac

passion, where the ejected material smelled and looked like excrement. Two

of these were so exhausted at the time I saw them, that more blood could

not be taken from them, and as their pain had ceased, and they continued to

vomit up every thing which they drank, I suspected that a mortification of

the bowel had already taken place, and as they were both women advanced in

life, and a mortification is produced with less preceding pain in old and

weak people, these both died. The other two, who were both young men, had

still pain and strength sufficient for further venesection, and they

neither of them had any appearance of hernia, both recovered by repeated

bleeding, and a scruple of calomel given to one, and half a dram to the

other, in very small pills: the usual means of clysters, and purges joined

with opiates, had been in vain attempted. I have thought an ounce or two of

crude mercury in less violent diseases of this kind has been of use, by

contributing to restore its natural motion to some part of the intestinal

canal, either by its weight or stimulus; and that hence the whole tube

recovered its usual associations of progressive peristaltic motion. I have

in three cases seen crude mercury given in small doses, as one or two

ounces twice a day, have great effect in stopping pertinacious vomitings.

17. Besides the affections above described, the stomach is liable, like

many other membranes of the body, to torpor without consequent

inflammation: as happens to the membranes about the head in some cases of

hemicrania, or in general head-ach. This torpor of the stomach is attended

with indigestion, and consequent flatulency, and with pain, which is

usually called the cramp of the stomach, and is relievable by aromatics,

essential oils, alcohol, or opium.

The intrusion of a gall-stone into the common bile-duct from the

gall-bladder is sometimes mistaken for a pain of the stomach, as neither of

them are attended with fever; but in the passage of a gall-stone, the pain

is confined to a less space, which is exactly where the common bile-duct

enters the duodenum, as explained in Section XXX. 1. 3. Whereas in this

gastrodynia the pain is diffused over the whole stomach; and, like other

diseases from torpor, the pulse is weaker, and the extremities colder, and

the general debility greater, than in the passage of a gall-stone; for in

the former the debility is the consequence of the pain, in the latter it is

the cause of it.

Though the first fits of the gout, I believe, commence with a torpor of the

liver; and the ball of the toe becomes inflamed instead of the membranes of

the liver in consequence of this torpor, as a coryza or catarrh frequently

succeeds a long exposure of the feet to cold, as in snow, or on a moist

brick-floor; yet in old or exhausted constitutions, which have been long

habituated to its attacks, it sometimes commences with a torpor of the

stomach, and is transferable to every membrane of the body. When the gout

begins with torpor of the stomach, a painful sensation of cold occurs,

which the patient compares to ice, with weak pulse, cold extremities, and

sickness; this in its slighter degree is relievable by spice, wine, or

opium; in its greater degree it is succeeded by sudden death, which is

owing to the sympathy of the stomach with the heart, as explained below.

If the stomach becomes inflamed in consequence of this gouty torpor of it,

or in consequence of its sympathy with some other part, the danger is less.

A sickness and vomiting continues many days, or even weeks, the stomach

rejecting every thing stimulant, even opium or alcohol, together with much

viscid mucus; till the inflammation at length ceases, as happens when other

membranes, as those of the joints, are the seat of gouty inflammation; as

observed in Sect. XXIV. 2. 8.

The sympathy, or association of motions, between those of the stomach and

those of the heart, are evinced in many diseases. First, many people are

occasionally affected with an intermission of their pulse for a few days,

which then ceases again. In this case there is a stop of the motion of the

heart, and at the same time a tendency to eructation from the stomach. As

soon as the patient feels a tendency to the intermission of the motion of

his heart, if he voluntarily brings up wind from his stomach, the stop of

the heart does not occur. From hence I conclude that the stop of digestion

is the primary disease; and that air is instantly generated from the

aliment, which begins to ferment, if the digestive process is impeded for a

moment, (see Sect. XXIII. 4.); and that the stop of the heart is in

consequence of the association of the motions of these viscera, as

explained in Sect. XXXV. 1. 4.; but if the little air, which is instantly

generated during the temporary torpor of the stomach, be evacuated, the

digestion recommences, and the temporary torpor of the heart does not

follow. One patient, whom I lately saw, and who had been five or six days

much troubled with this intermission of a pulsation of his heart, and who

had hemicrania with some fever, was immediately relieved from them all by

losing ten ounces of blood, which had what is termed an inflammatory crust

on it.

Another instance of this association between the motions of the stomach and

heart is evinced by the exhibition of an over dose of foxglove, which

induces an incessant vomiting, which is attended with very slow, and

sometimes intermitting pulse.--Which continues in spite of the exhibition

of wine and opium for two or three days. To the same association must be

ascribed the weak pulse, which constantly attends the exhibition of emetics

during their operation. And also the sudden deaths, which have been

occasioned in boxing by a blow on the stomach; and lastly, the sudden death

of those, who have been long debilitated by the gout, from the torpor of

the stomach. See Sect. XXXV. 1. 4.

* * * * *

SECT. XXVI.

OF THE CAPILLARY GLANDS AND MEMBRANES.

I. 1. _The capillary vessels are glands._ 2. _Their excretory ducts.

Experiments on the mucus of the intestines, abdomen, cellular membrane,

and on the humours of the eye._ 3. _Scurf on the head, cough, catarrh,

diarrhoea, gonorrhoea._ 4. _Rheumatism. Gout. Leprosy._ II. 1. _The

most minute membranes are unorganized._ 2. _Larger membranes are

composed of the ducts of the capillaries, and the mouths of the

absorbents._ 3. _Mucilaginous fluid is secreted on their surfaces._

III. _Three kinds of rheumatism._

I. 1. The capillary-vessels are like all the other glands except the

absorbent system, inasmuch as they receive blood from the arteries,

separate a fluid from it, and return the remainder by the veins.

2. This series of glands is of the most extensive use, as their excretory

ducts open on the whole external skin forming its perspirative pores, and

on the internal surfaces of every cavity of the body. Their secretion on

the skin is termed insensible perspiration, which in health is in part

reabsorbed by the mouths of the lymphatics, and in part evaporated in the

air; the secretion on the membranes, which line the larger cavities of the

body, which have external openings, as the mouth and intestinal canal, is

termed mucus, but is not however coagulable by heat; and the secretion on

the membranes of those cavities of the body, which have no external

openings, is called lymph or water, as in the cavities of the cellular

membrane, and of the abdomen; this lymph however is coagulable by the heat

of boiling water. Some mucus nearly as viscid as the white of egg, which

was discharged by stool, did not coagulate, though I evaporated it to one

fourth of the quantity, nor did the aqueous and vitreous humours of a

sheep's eye coagulate by the like experiment: but the serosity from an

anasarcous leg, and that from the abdomen of a dropsical person, and the

crystalline humour of a sheep's eye, coagulated in the same heat.

3. When any of these capillary glands are stimulated into greater

irritative actions, than is natural, they secrete a more copious material;

and as the mouths of the absorbent system, which open in their vicinity,

are at the same time stimulated into greater action, the thinner and more

saline part of the secreted fluid is taken up again; and the remainder is

not only more copious but also more viscid than natural. This is more or

less troublesome or noxious according to the importance of the functions of

the part affected: on the skin and bronchiæ, where this secretion ought

naturally to evaporate, it becomes so viscid as to adhere to the membrane;

on the tongue it forms a pellicle, which can with difficulty be scraped

off; produces the scurf on the heads of many people; and the mucus, which

is spit up by others in coughing. On the nostrils and fauces, when the

secretion of these capillary glands is increased, it is termed simple

catarrh; when in the intestines, a mucous diarrhoea; and in the urethra, or

vagina, it has the name of gonorrhoea, or fluor albus.

4. When these capillary glands become inflamed, a still more viscid or even

cretaceous humour is produced upon the surfaces of the membranes, which is

the cause or the effect of rheumatism, gout, leprosy, and of hard tumours

of the legs, which are generally termed scorbutic; all which will be

treated of hereafter.

II. 1. The whole surface of the body, with all its cavities and contents,

are covered with membrane. It lines every vessel, forms every cell, and

binds together all the muscular and perhaps the osseous fibres of the body;

and is itself therefore probably a simpler substance than those fibres. And

as the containing vessels of the body from the largest to the least are

thus lined and connected with membranes, it follows that these membranes

themselves consisted of unorganized materials.

For however small we may conceive the diameters of the minutest vessels of

the body, which escape our eyes and glasses, yet these vessels must consist

of coats or sides, which are made up of an unorganized material, and which

are probably produced from a gluten, which hardens after its production,

like the silk or web of caterpillars and spiders. Of this material consist

the membranes, which line the shells of eggs, and the shell itself, both

which are unorganized, and are formed from mucus, which hardens after it is

formed, either by the absorption of its more fluid part, or by its uniting

with some part of the atmosphere. Such is also the production of the shells

of snails, and of shell-fish, and I suppose of the enamel of the teeth.

2. But though the membranes, that compose the sides of the most minute

vessels, are in truth unorganized materials, yet the larger membranes,

which are perceptible to the eye, seem to be composed of an intertexture of

the mouths of the absorbent system, and of the excretory ducts of the

capillaries, with their concomitant arteries, veins, and nerves: and from

this construction it is evident, that these membranes must possess great

irritability to peculiar stimuli, though they are incapable of any motions,

that are visible to the naked eye: and daily experience shews us, that in

their inflamed state they have the greatest sensibility to pain, as in the

pleurisy and paronychia.

3. On all these membranes a mucilaginous or aqueous fluid is secreted,

which moistens and lubricates their surfaces, as was explained in Section

XXIII. 2. Some have doubted, whether this mucus is separated from the blood

by an appropriated set of glands, or exudes through the membranes, or is an

abrasion or destruction of the surface of the membrane itself, which is

continually repaired on the other side of it, but the great analogy between

the capillary vessels, and the other glands, countenances the former

opinion; and evinces, that these capillaries are the glands, that secrete

it; to which we must add, that the blood in passing these capillary vessels

undergoes a change in its colour from florid to purple, and gives out a

quantity of heat; from whence, as in other glands, we must conclude that

something is secreted from it.

III. The seat of rheumatism is in the membranes, or upon them; but there

are three very distinct diseases, which commonly are confounded under this

name. First, when a membrane becomes affected with torpor, or inactivity of

the vessels which compose it, pain and coldness succeed, as in the

hemicrania, and other head-achs, which are generally termed nervous

rheumatism; they exist whether the part be at rest or in motion, and are

generally attended with other marks of debility.

Another rheumatism is said to exist, when inflammation and swelling, as

well as pain, affect some of the membranes of the joints, as of the ancles,

wrists, knees, elbows, and sometimes of the ribs. This is accompanied with

fever, is analogous to pleurisy and other inflammations, and is termed the

acute rheumatism.

A third disease is called chronic rheumatism, which is distinguished from

that first mentioned, as in this the pain only affects the patient during

the motion of the part, and from the second kind of rheumatism above

described, as it is not attended with quick pulse or inflammation. It is

generally believed to succeed the acute rheumatism of the same part, and

that some coagulable lymph, or cretaceous, or calculous material, has been

left on the membrane; which gives pain, when the muscles move over it, as

some extraneous body would do, which was too insoluble to be absorbed.

Hence there is an analogy between this chronic rheumatism and the diseases

which produce gravel or gout-stones; and it may perhaps receive relief from

the same remedies, such as aerated sal soda.

* * * * *

SECT. XXVII.

OF HÆMORRHAGES.

I. _The veins are absorbent vessels._ 1. _Hæmorrhages from

inflammation. Case of hæmorrhage from the kidney cured by cold bathing.

Case of hæmorrhage from the nose cured by cold immersion._ II.

_Hæmorrhage from venous paralysis. Of Piles. Black stools. Petechiæ.

Consumption. Scurvy of the lungs. Blackness of the face and eyes in

epileptic fits. Cure of hæmorrhages from venous inability._

I. As the imbibing mouths of the absorbent system already described open on

the surface, and into the larger cavities of the body, so there is another

system of absorbent vessels, which are not commonly esteemed such, I mean

the veins, which take up the blood from the various glands and capillaries,

after their proper fluids or secretions have been separated from it.

The veins resemble the other absorbent vessels; as the progression of their

contents is carried on in the same manner in both, they alike absorb their

appropriated fluids, and have valves to prevent its regurgitation by the

accidents of mechanical violence. This appears first, because there is no

pulsation in the very beginnings of the veins, as is seen by microscopes;

which must happen, if the blood was carried into them by the actions of the

arteries. For though the concurrence of various venous streams of blood

from different distances must prevent any pulsation in the larger branches,

yet in the very beginnings of all these branches a pulsation must

unavoidably exist, if the circulation in them was owing to the intermitted

force of the arteries. Secondly, the venous absorption of blood from the

penis, and from the teats of female animals after their erection, is still

more similar to the lymphatic absorption, as it is previously poured into

cells, where all arterial impulse must cease.

There is an experiment, which seems to evince this venous absorption, which

consists in the external application of a stimulus to the lips, as of

vinegar, by which they become instantly pale; that is, the bibulous mouths

of the veins by this stimulus are excited to absorb the blood faster, than

it can be supplied by the usual arterial exertion. See Sect. XXIII. 5.

There are two kinds of hæmorrhages frequent in diseases, one is where the

glandular or capillary action is too powerfully exerted, and propels the

blood forwards more hastily, than the veins can absorb it; and the other

is, where the absorbent power of the veins is diminished, or a branch of

them is become totally paralytic.

1. The former of these cases is known by the heat of the part, and the

general fever or inflammation that accompanies the hæmorrhage. An

hæmorrhage from the nose or from the lungs is sometimes a crisis of

inflammatory diseases, as of the hepatitis and gout, and generally ceases

spontaneously, when the vessels are considerably emptied. Sometimes the

hæmorrhage recurs by daily periods accompanying the hot fits of fever, and

ceasing in the cold fits, or in the intermissions; this is to be cured by

removing the febrile paroxysms, which will be treated of in their place.

Otherwise it is cured by venesection, by the internal or external

preparations of lead, or by the application of cold, with an abstemious

diet, and diluting liquids, like other inflammations. Which by inducing a

quiescence on those glandular parts, that are affected, prevents a greater

quantity of blood from being protruded forwards, than the veins are capable

of absorbing.

Mr. B---- had an hæmorrhage from his kidney, and parted with not less than

a pint of blood a day (by conjecture) along with his urine for above a

fortnight: venesections, mucilages, balsams, preparations of lead, the

bark, alum, and dragon's blood, opiates, with a large blister on his loins,

were separately tried, in large doses, to no purpose. He was then directed

to bathe in a cold spring up to the middle of his body only, the upper part

being covered, and the hæmorrhage diminished at the first, and ceased at

the second immersion.

In this case the external capillaries were rendered quiescent by the

coldness of the water, and thence a less quantity of blood was circulated

through them; and the internal capillaries, or other glands, became

quiescent from their irritative associations with the external ones; and

the hæmorrhage was stopped a sufficient time for the ruptured vessels to

contract their apertures, or for the blood in those apertures to coagulate.

Mrs. K---- had a continued haemorrhage from her nose for some days; the

ruptured vessel was not to be reached by plugs up the nostrils, and the

sensibility of her fauces was such that nothing could be born behind the

uvula. After repeated venesection, and other common applications, she was

directed to immerse her whole head into a pail of water, which was made

colder by the addition of several handfuls of salt, and the hæmorrhage

immediately ceased, and returned no more; but her pulse continued hard, and

she was necessitated to lose blood from the arm on the succeeding day.

Query, might not the cold bath instantly stop hæmorrhages from the lungs in

inflammatory cases?--for the shortness of breath of those, who go suddenly

into cold water, is not owing to the accumulation of blood in the lungs,

but to the quiescence of the pulmonary capillaries from association, as

explained in Section XXXII. 3. 2.

II. The other kind of hæmorrhage is known from its being attended with a

weak pulse, and other symptoms of general debility, and very frequently

occurs in those, who have diseased livers, owing to intemperance in the use

of fermented liquors. These constitutions are shewn to be liable to

paralysis of the lymphatic absorbents, producing the various kinds of

dropsies in Section XXIX. 5. Now if any branch of the venous system loses

its power of absorption, the part swells, and at length bursts and

discharges the blood, which the capillaries or other glands circulate

through them.

It sometimes happens that the large external veins of the legs burst, and

effuse their blood; but this occurs most frequently in the veins of the

intestines, as the vena portarum is liable to suffer from a schirrus of the

liver opposing the progression of the blood, which is absorbed from the

intestines. Hence the piles are a symptom of hepatic obstruction, and hence

the copious discharges downwards or upwards of a black material, which has

been called melancholia, or black bile; but is no other than the blood,

which is probably discharged from the veins of the intestines.

J.F. Meckel, in his Experimenta de Finibus Vasorum, published at Berlin,

1772, mentions his discovery of a communication of a lymphatic vessel with

the gastric branch of the vena portarum. It is possible, that when the

motion of the lymphatic becomes retrograde in some diseases, that blood may

obtain a passage into it, where it anastomoses with the vein, and thus be

poured into the intestines. A discharge of blood with the urine sometimes

attends diabetes, and may have its source in the same manner.

Mr. A----, who had been a hard drinker, and had the gutta rosacea on his

face and breast, after a stroke of the palsy voided near a quart of a black

viscid material by stool: on diluting it with water it did not become

yellow, as it must have done if it had been inspissated bile, but continued

black like the grounds of coffee.

But any other part of the venous system may become quiescent or totally

paralytic as well as the veins of the intestines: all which occur more

frequently in those who have diseased livers, than in any others. Hence

troublesome bleedings of the nose, or from the lungs with a weak pulse;

hence hæmorrhages from the kidneys, too great menstruation; and hence the

oozing of blood from every part of the body, and the petechiæ in those

fevers, which are termed putrid, and which is erroneously ascribed to the

thinness of the blood: for the blood in inflammatory diseases is equally

fluid before it coagulates in the cold air.

Is not that hereditary consumption, which occurs chiefly in dark-eyed

people about the age of twenty, and commences with slight pulmonary

hæmorrhages without fever, a disease of this kind?--These hæmorrhages

frequently begin during sleep, when the irritability of the lungs is not

sufficient in these patients to carry on the circulation without the

assistance of volition; for in our waking hours, the motions of the lungs

are in part voluntary, especially if any difficulty of breathing renders

the efforts of volition necessary. See Class I. 2. 1. 3. and Class III. 2.

1. 12. Another species of pulmonary consumption which seems more certainly

of scrophulous origin is described in the next Section, No. 2.

I have seen two cases of women, of about forty years of age, both of whom

were seized with quick weak pulse, with difficult respiration, and who spit

up by coughing much viscid mucus mixed with dark coloured blood. They had

both large vibices on their limbs, and petechiæ; in one the feet were in

danger of mortification, in the other the legs were oedematous. To relieve

the difficult respiration, about six ounces of blood were taken from one of

them, which to my surprise was sizy, like inflamed blood: they had both

palpitations or unequal pulsations of the heart. They continued four or

five weeks with pale and bloated countenances, and did not cease spitting

phlegm mixed with black blood, and the pulse seldom slower than 130 or 135

in a minute. This blood, from its dark colour, and from the many vibices

and petechiæ, seems to have been venous blood; the quickness of the pulse,

and the irregularity of the motion of the heart, are to be ascribed to

debility of that part of the system; as the extravasation of blood

originated from the defect of venous absorption. The approximation of these

two cases to sea-scurvy is peculiar, and may allow them to be called

scorbutus pulmonalis. Had these been younger subjects, and the paralysis of

the veins had only affected the lungs, it is probable the disease would

have been a pulmonary consumption.

Last week I saw a gentleman of Birmingham, who had for ten days laboured

under great palpitation of his heart, which was so distinctly felt by the

hand, as to discountenance the idea of there being a fluid in the

pericardium. He frequently spit up mucus stained with dark coloured blood,

his pulse very unequal and very weak, with cold hands and nose. He could

not lie down at all, and for about ten days past could not sleep a minute

together, but waked perpetually with great uneasiness. Could those symptoms

be owing to very extensive adhesions of the lungs? or is this a scorbutus

pulmonalis? After a few days he suddenly got so much better as to be able

to sleep many hours at a time by the use of one grain of powder of foxglove

twice a day, and a grain of opium at night. After a few days longer, the

bark was exhibited, and the opium continued with some wine; and the

palpitations of his heart became much relieved, and he recovered his usual

degree of health, but died suddenly some months afterwards.

In epileptic fits the patients frequently become black in the face, from

the temporary paralysis of the venous system of this part. I have known two

instances where the blackness has continued many days. M. P----, who had

drank intemperately, was seized with the epilepsy when he was in his

fortieth year; in one of these fits the white part of his eyes was left

totally black with effused blood; which was attended with no pain or heat,

and was in a few weeks gradually absorbed, changing colour as is usual with

vibices from bruises.

The hæmorrhages produced from the inability of the veins to absorb the

refluent blood, is cured by opium, the preparations of steel, lead, the

bark, vitriolic acid, and blisters; but these have the effect with much

more certainty, if a venesection to a few ounces, and a moderate cathartic

with four or six grains of calomel be premised, where the patient is not

already too much debilitated; as one great means of promoting the

absorption of any fluid consists in previously emptying the vessels, which

are to receive it.

* * * * *

SECT. XXVIII.

OF THE PARALYSIS OF THE ABSORBENT SYSTEM.

I. _Paralysis of the lacteals, atrophy. Distaste to animal food._ II.

_Cause of dropsy. Cause of herpes. Scrophula. Mesenteric consumption.

Pulmonary consumption. Why ulcers in the lungs are so difficult to

heal._

The term paralysis has generally been used to express the loss of voluntary

motion, as in the hemiplagia, but may with equal propriety be applied to

express the disobediency of the muscular fibres to the other kinds of

stimulus; as to those of irritation or sensation.

I. There is a species of atrophy, which has not been well understood; when

the absorbent vessels of the stomach and intestines have been long inured

to the stimulus of too much spirituous liquor, they at length, either by

the too sudden omission of fermented or spirituous potation, or from the

gradual decay of nature, become in a certain degree paralytic; now it is

observed in the larger muscles of the body, when one side is paralytic, the

other is more frequently in motion, owing to the less expenditure of

sensorial power in the paralytic limbs; so in this case the other part of

the absorbent system acts with greater force, or with greater perseverance,

in consequence of the paralysis of the lacteals; and the body becomes

greatly emaciated in a small time.

I have seen several patients in this disease, of which the following are

the circumstances. 1. They were men about fifty years of age, and had lived

freely in respect to fermented liquors. 2. They lost their appetite to

animal food. 3. They became suddenly emaciated to a great degree. 4. Their

skins were dry and rough. 5. They coughed and expectorated with difficulty

a viscid phlegm. 6. The membrane of the tongue was dry and red, and liable

to become ulcerous.

The inability to digest animal food, and the consequent distaste to it,

generally precedes the dropsy, and other diseases, which originate from

spirituous potation. I suppose when the stomach becomes inirritable, that

there is at the same time a deficiency of gastric acid; hence milk seldom

agrees with these patients, unless it be previously curdled, as they have

not sufficient gastric acid to curdle it; and hence vegetable food, which

is itself acescent, will agree with their stomachs longer than animal food,

which requires more of the gastric acid for its digestion.

In this disease the skin is dry from the increased absorption of the

cutaneous lymphatics, the fat is absorbed from the increased absorption of

the cellular lymphatics, the mucus of the lungs is too viscid to be easily

spit up by the increased absorption of the thinner parts of it, the

membrana sneideriana becomes dry, covered with hardened mucus, and at

length becomes inflamed and full of aphthæ, and either these sloughs, or

pulmonary ulcers, terminate the scene.

II. The immediate cause of dropsy is the paralysis of some other branches

of the absorbent system, which are called lymphatics, and which open into

the larger cavities of the body, or into the cells of the cellular

membrane; whence those cavities or cells become distended with the fluid,

which is hourly secreted into them for the purpose of lubricating their

surfaces. As is more fully explained in No. 5. of the next Section.

As those lymphatic vessels consist generally of a long neck or mouth, which

drinks up its appropriated fluid, and of a conglobate gland, in which this

fluid undergoes some change, it happens, that sometimes the mouth of the

lymphatic, and sometimes the belly or glandular part of it, becomes totally

or partially paralytic. In the former case, where the mouths of the

cutaneous lymphatics become torpid or quiescent, the fluid secreted on the

skin ceases to be absorbed, and erodes the skin by its saline acrimony, and

produces eruptions termed herpes, the discharge from which is as salt, as

the tears, which are secreted too fast to be reabsorbed, as in grief, or

when the puncta lacrymalia are obstructed, and which running down the cheek

redden and inflame the skin.

When the mouths of the lymphatics, which open on the mucous membrane of the

nostrils, become torpid, as on walking into the air in a frosty morning;

the mucus, which continues to be secreted, has not its aqueous and saline

part reabsorbed, which running over the upper lip inflames it, and has a

salt taste, if it falls on the tongue.

When the belly, or glandular part of these lymphatics, becomes torpid, the

fluid absorbed by its mouth stagnates, and forms a tumour in the gland.

This disease is called the scrophula. If these glands suppurate externally,

they gradually heal, as those of the neck; if they suppurate without an

opening on the external habit, as the mesenteric glands, a hectic fever

ensues, which destroys the patient; if they suppurate in the lungs, a

pulmonary consumption ensues, which is believed thus to differ from that

described in the preceding Section, in respect to its seat or proximate

cause.

It is remarkable, that matter produced by suppuration will lie concealed in

the body many weeks, or even months, without producing hectic fever; but as

soon as the wound is opened, so as to admit air to the surface of the

ulcer, a hectic fever supervenes, even in very few hours, which is probably

owing to the azotic part of the atmosphere rather than to the oxygene;

because those medicines, which contain much oxygene, as the calces or

oxydes of metals, externally applied, greatly contribute to heal ulcers, of

these are the solutions of lead and mercury, and copper in acids, or their

precipitates.

Hence when wounds are to be healed by the first intention, as it is called,

it is necessary carefully to exclude the air from them. Hence we have one

cause, which prevents pulmonary ulcers from healing, which is their being

perpetually exposed to the air.

Both the dark-eyed patients, which are affected with pulmonary ulcers from

deficient venous absorption, as described in Section. XXVII. 2. and the

light-eyed patients from deficient lymphatic absorption, which we are now

treating of, have generally large apertures of the iris; these large pupils

of the eyes are a common mark of want of irritability; and it generally

happens, that an increase of sensibility, that is, of motions in

consequence of sensation, attends these constitutions. See Sect. XXXI. 2.

Whence inflammations may occur in these from stagnated fluids more

frequently than in those constitutions, which possess more irritability and

less sensibility.

Great expectations in respect to the cure of consumptions, as well as of

many other diseases, are produced by the very ingenious exertions of DR.

BEDDOES; who has established an apparatus for breathing various mixtures of

airs or gasses, at the hot-wells near Bristol, which well deserves the

attention of the public.

DR. BEDDOES very ingeniously concludes, from the florid colour of the blood

of consumptive patients, that it abounds in oxygene; and that the redness

of their tongues, and lips, and the fine blush of their cheeks shew the

presence of the same principle, like flesh reddened by nitre. And adds,

that the circumstance of the consumptions of pregnant women being stopped

in their progress during pregnancy, at which time their blood may be

supposed to be in part deprived of its oxygene, by oxygenating the blood of

the foetus, is a forceable argument in favour of this theory; which must

soon be confirmed or confuted by his experiments. See Essay on Scurvy,

Consumption, &c. by Dr. Beddoes. Murray. London. Also Letter to Dr. Darwin,

by the same. Murray. London.

* * * * *

SECT. XXIX.

ON THE RETROGRADE MOTIONS OF THE ABSORBENT SYSTEM.

I. _Account of the absorbent system._ II. _The valves of the absorbent

vessels may suffer their fluids to regurgitate in some diseases._ III.

_Communication from the alimentary canal to the bladder by means of the

absorbent vessels._ IV. _The phenomena of diabetes explained._ V. 1.

_The phenomena of dropsies explained._ 2. _Cases of the use of

foxglove._ VI. _Of cold sweats._ VII. _Translations of matter, of

chyle, of milk, of urine, operation of purging drugs applied

externally._ VIII. _Circumstances by which the fluids, that are effused

by the retrograde motions of the absorbent vessels, are distinguished._

IX. _Retrograde motions of vegetable juices._ X. _Objections answered._

XI. _The causes, which induce the retrograde motions of animal vessels,

and the medicines by which the natural motions are restored._

_N.B. The following Section is a translation of a part of a Latin

thesis written by the late Mr. Charles Darwin, which was printed with

his prize-dissertation on a criterion between matter and mucus in 1780.

Sold by Cadell, London._

I. _Account of the Absorbent System._

1. The absorbent system of vessels in animal bodies consists of several

branches, differing in respect to their situations, and to the fluids,

which they absorb.

The intestinal absorbents open their mouths on the internal surfaces of the

intestines; their office is to drink up the chyle and the other fluids from

the alimentary canal; and they are termed lacteals, to distinguish them

from the other absorbent vessels, which have been termed lymphatics.

Those, whose mouths are dispersed on the external skin, imbibe a great

quantity of water from the atmosphere, and a part of the perspirable

matter, which does not evaporate, and are termed cutaneous absorbents.

Those, which arise from the internal surface of the bronchia, and which

imbibe moisture from the atmosphere, and a part of the bronchial mucus, are

called pulmonary absorbents.

Those, which open their innumerable mouths into the cells of the whole

cellular membrane; and whose use is to take up the fluid, which is poured

into those cells, after it has done its office there; may be called

cellular absorbents.

Those, which arise from the internal surfaces of the membranes, which line

the larger cavities of the body, as the thorax, abdomen, scrotum,

pericardium, take up the mucus poured into those cavities; and are

distinguished by the names of their respective cavities.

Whilst those, which arise from the internal surfaces of the urinary

bladder, gall-bladder, salivary ducts, or other receptacles of secreted

fluids, may take their names from those fluids; the thinner parts of which

it is their office to absorb: as urinary, bilious, or salivary absorbents.

2. Many of these absorbent vessels, both lacteals and lymphatics, like some

of the veins, are replete with valves: which seem designed to assist the

progress of their fluids, or at least to prevent their regurgitation; where

they are subjected to the intermitted pressure of the muscular, or arterial

actions in their neighbourhood.

These valves do not however appear to be necessary to all the absorbents,

any more than to all the veins; since they are not found to exist in the

absorbent system of fish; according to the discoveries of the ingenious,

and much lamented Mr. Hewson. Philos. Trans. v. 59, Enquiries into the

Lymph. Syst. p. 94.

3. These absorbent vessels are also furnished with glands, which are called

conglobate glands; whose use is not at present sufficiently investigated;

but it is probable that they resemble the conglomerate glands both in

structure and in use, except that their absorbent mouths are for the

conveniency of situation placed at a greater distance from the body of the

gland. The conglomerate glands open their mouths immediately into the

sanguiferous vessels, which bring the blood, from whence they absorb their

respective fluids, quite up to the gland: but these conglobate glands

collect their adapted fluids from very distant membranes, or cysts, by

means of mouths furnished with long necks for this purpose; and which are

called lacteals, or lymphatics.

4. The fluids, thus collected from various parts of the body, pass by means

of the thoracic duct into the left subclavian near the jugular vein; except

indeed that those collected from the right side of the head and neck, and

from the right arm, are carried into the right subclavian vein: and

sometimes even the lymphatics from the right side of the lungs are inserted

into the right subclavian vein; whilst those of the left side of the head

open but just into the summit of the thoracic duct.

5. In the absorbent system there are many anastomoses of the vessels, which

seem of great consequence to the preservation of health. These anastomoses

are discovered by dissection to be very frequent between the intestinal and

urinary lymphatics, as mentioned by Mr. Hewson, (Phil. Trans. v. 58.)

6. Nor do all the intestinal absorbents seem to terminate in the thoracic

duct, as appears from some curious experiments of D. Munro, who gave madder

to some animals, having previously put a ligature on the thoracic duct, and

found their bones, and the serum of their blood, coloured red.

II. _The Valves of the Absorbent System may suffer their Fluids to

regurgitate in some Diseases._

1. The many valves, which occur in the progress of the lymphatic and

lacteal vessels, would seem insuperable obstacles to the regurgitation of

their contents. But as these valves are placed in vessels, which are indued

with life, and are themselves indued with life also; and are very irritable

into those natural motions, which absorb, or propel the fluids they

contain; it is possible, in some diseases, where these valves or vessels

are stimulated into unnatural exertions, or are become paralytic, that

during the diastole of the part of the vessel to which the valve is

attached, the valve may not so completely close, as to prevent the relapse

of the lymph or chyle. This is rendered more probable, by the experiments

of injecting mercury, or water, or suet, or by blowing air down these

vessels: all which pass the valves very easily, contrary to the natural

course of their fluids, when the vessels are thus a little forcibly

dilated, as mentioned by Dr. Haller, Elem. Physiol. t. iii. s. 4.

"The valves of the thoracic duct are few, some assert they are not more

than twelve, and that they do not very accurately perform their office, as

they do not close the whole area of the duct, and thence may permit chyle

to repass them downwards. In living animals, however, though not always,

yet more frequently than in the dead, they prevent the chyle from

returning. The principal of these valves is that, which presides over the

insertion of the thoracic duct, into the subclavian vein; many have

believed this also to perform the office of a valve, both to admit the

chyle into the vein, and to preclude the blood from entering the duct; but

in my opinion it is scarcely sufficient for this purpose." Haller, Elem.

Phys. t. vii. p. 226.

2. The mouths of the lymphatics seem to admit water to pass through them

after death, the inverted way, easier than the natural one; since an

inverted bladder readily lets out the water with which it is filled; whence

it may be inferred, that there is no obstacle at the mouths of these

vessels to prevent the regurgitation of their contained fluids.

I was induced to repeat this experiment, and having accurately tied the

ureters and neck of a fresh ox's bladder, I made an opening at the fundus

of it; and then, having turned it inside outwards, filled it half full with

water, and was surprised to see it empty itself so hastily. I thought the

experiment more apposite to my purpose by suspending the bladder with its

neck downwards, as the lymphatics are chiefly spread upon this part of it,

as shewn by Dr. Watson, Philos. Trans. v. 59. p. 392.

3. In some diseases, as in the diabetes and scrophula, it is probable the

valves themselves are diseased, and are thence incapable of preventing the

return of the fluids they should support. Thus the valves of the aorta

itself have frequently been found schirrous, according to the dissections

of Mons. Lieutaud, and have given rise to an interrupted pulse, and

laborious palpitations, by suffering a return of part of the blood into the

heart. Nor are any parts of the body so liable to schirrosity as the

lymphatic glands and vessels, insomuch that their schirrosities have

acquired a distinct name, and been termed scrophula.

4. There are valves in other parts of the body, analogous to those of the

absorbent system, and which are liable, when diseased, to regurgitate their

contents: thus the upper and lower orifices of the stomach are closed by

valves, which, when too great quantities of warm water have been drank with

a design to promote vomiting, have sometimes resisted the utmost efforts of

the abdominal muscles, and diaphragm: yet, at other times, the upper valve,

or cardia, easily permits the evacuation of the contents of the stomach;

whilst the inferior valve, or pylorus, permits the bile, and other contents

of the duodenum, to regurgitate into the stomach.

5. The valve of the colon is well adapted to prevent the retrograde motion

of the excrements; yet, as this valve is possessed of a living power, in

the iliac passion, either from spasm, or other unnatural exertions, it

keeps itself open, and either suffers or promotes the retrograde movements

of the contents of the intestines below; as in ruminating animals the mouth

of the first stomach seems to be so constructed, as to facilitate or assist

the regurgitation of the food; the rings of the oesophagus afterwards

contracting themselves in inverted order. De Haeu, by means of a syringe,

forced so much water into the rectum intestinum of a dog, that he vomited

it in a full stream from his mouth; and in the iliac passion above

mentioned, excrements and clyster are often evacuated by the mouth. See

Section XXV. 15.

6. The puncta lacrymalia, with the lacrymal sack and nasal duct, compose a

complete gland, and much resemble the intestinal canal: the puncta

lacrymalia are absorbent mouths, that take up the tears from the eye, when

they have done their office there, and convey them into the nostrils; but

when the nasal duct is obstructed, and the lacrymal sack distended with its

fluid, on pressure with the finger the mouths of this gland (puncta

lacrymalia) will readily disgorge the fluid, they had previously absorbed,

back into the eye.

7. As the capillary vessels receive blood from the arteries, and separating

the mucus, or perspirable matter from it, convey the remainder back by the

veins; these capillary vessels are a set of glands, in every respect

similar to the secretory vessels of the liver, or other large congeries of

glands. The beginnings of these capillary vessels have frequent anastomoses

into each other, in which circumstance they are resembled by the lacteals;

and like the mouths or beginnings of other glands, they are a set of

absorbent vessels, which drink up the blood which is brought to them by the

arteries, as the chyle is drank up by the lacteals: for the circulation of

the blood through the capillaries is proved to be independent of arterial

impulse; since in the blush of shame, and in partial inflammations, their

action is increased, without any increase of the motion of the heart.

8. Yet not only the mouths, or beginnings of these anastomosing capillaries

are frequently seen by microscopes, to regurgitate some particles of blood,

during the struggles of the animal; but retrograde motion of the blood, in

the veins of those animals, from the very heart of the extremity of the

limbs, is observable, by intervals, during the distresses of the dying

creature. Haller, Elem. Physiol. t. i. p. 216. Now, as the veins have

perhaps all of them a valve somewhere between their extremities and the

heart, here is ocular demonstration of the fluids in this diseased

condition of the animal, repassing through venous valves: and it is hence

highly probable, from the strictest analogy, that if the course of the

fluids, in the lymphatic vessels, could be subjected to microscopic

observation, they would also, in the diseased state of the animal, be seen

to repass the valves, and the mouths of those vessels, which had previously

absorbed them, or promoted their progression.

III. _Communication from the Alimentary Canal to the Bladder, by means of

the Absorbent Vessels._

Many medical philosophers, both ancient and modern, have suspected that

there was a nearer communication between the stomach and the urinary

bladder, than that of the circulation: they were led into this opinion from

the great expedition with which cold water, when drank to excess, passes

off by the bladder; and from the similarity of the urine, when produced in

this hasty manner, with the material that was drank.

The former of these circumstances happens perpetually to those who drink

abundance of cold water, when they are much heated by exercise, and to many

at the beginning of intoxication.

Of the latter, many instances are recorded by Etmuller, t. xi. p. 716.

where simple water, wine, and wine with sugar, and emulsions, were returned

by urine unchanged.

There are other experiments, that seem to demonstrate the existence of

another passage to the bladder, besides that through the kidneys. Thus Dr.

Kratzenstein put ligatures on the ureters of a dog, and then emptied the

bladder by a catheter; yet in a little time the dog drank greedily, and

made a quantity of water, (Disputat. Morbor. Halleri. t. iv. p. 63.) A

similar experiment is related in the Philosophical Transactions, with the

same event, (No. 65, 67, for the year 1670.)

Add to this, that in some morbid cases the urine has continued to pass,

after the suppuration or total destruction of the kidneys; of which many

instances are referred to in the Elem. Physiol. t. vii. p. 379. of Dr.

Haller.

From all which it must be concluded, that some fluids have passed from the

stomach or abdomen, without having gone through the sanguiferous

circulation: and as the bladder is supplied with many lymphatics, as

described by Dr. Watson, in the Philos. Trans. v. 59. p. 392. and as no

other vessels open into it besides these and the ureters, it seems evident,

that the unnatural urine, produced as above described, when the ureters

were tied, or the kidneys obliterated, was carried into the bladder by the

retrograde motions of the urinary branch of the lymphatic system.

The more certainly to ascertain the existence of another communication

between the stomach and bladder, besides that of the circulation, the

following experiment was made, to which I must beg your patient

attention:--A friend of mine (June 14, 1772) on drinking repeatedly of cold

small punch, till he began to be intoxicated, made a quantity of colourless

urine. He then drank about two drams of nitre dissolved in some of the

punch, and eat about twenty stalks of boiled asparagus: on continuing to

drink more of the punch, the next urine that he made was quite clear, and

without smell; but in a little time another quantity was made, which was

not quite so colourless, and had a strong smell of the asparagus: he then

lost about four ounces of blood from the arm.

The smell of asparagus was not at all perceptible in the blood, neither

when fresh taken, nor the next morning, as myself and two others accurately

attended to; yet this smell was strongly perceived in the urine, which was

made just before the blood was taken from his arm.

Some bibulous paper, moistened in the serum of this blood, and suffered to

dry, shewed no signs of nitre by its manner of burning. But some of the

same paper, moistened in the urine, and dried, on being ignited, evidently

shewed the presence of nitre. This blood and the urine stood some days

exposed to the sun in the open air, till they were evaporated to about a

fourth of their original quantity, and began to stink: the paper, which was

then moistened with the concentrated urine, shewed the presence of much

nitre by its manner of burning; whilst that moistened with the blood shewed

no such appearance at all.

Hence it appears, that certain fluids at the beginning of intoxication,

find another passage to the bladder besides the long course of the arterial

circulation; and as the intestinal absorbents are joined with the urinary

lymphatics by frequent anastomoses, as Hewson has demonstrated; and as

there is no other road, we may justly conclude, that these fluids pass into

the bladder by the urinary branch of the lymphatics, which has its motions

inverted during the diseased state of the animal.

A gentleman, who had been some weeks affected with jaundice, and whose

urine was in consequence of a very deep yellow, took some cold small punch,

in which was dissolved about a dram of nitre; he then took repeated

draughts of the punch, and kept himself in a cool room, till on the

approach of slight intoxication he made a large quantity of water; this

water had a slight yellow tinge, as might be expected from a small

admixture of bile secreted from the kidneys; but if the whole of it had

passed through the sanguiferous vessels, which were now replete with bile

(his whole skin being as yellow as gold) would not this urine also, as well

as that he had made for weeks before, have been of a deep yellow? Paper

dipped in this water, and dryed, and ignited, shewed evident marks of the

presence of nitre, when the flame was blown out.

IV. _The Phænomena of the Diabetes explained, and of some Diarrhoeas._

The phenomena of many diseases are only explicable from the retrograde

motions of some of the branches of the lymphatic system; as the great and

immediate flow of pale urine in the beginning of drunkenness; in hysteric

paroxysms; from being exposed to cold air; or to the influence of fear or

anxiety.

Before we endeavour to illustrate this doctrine, by describing the

phænomena of these diseases, we must premise one circumstance; that all the

branches of the lymphatic system have a certain sympathy with each other,

insomuch that when one branch is stimulated into unusual kinds or

quantities of motion, some other branch has its motions either increased,

or decreased, or inverted at the same time. This kind of sympathy can only

be proved by the concurrent testimony of numerous facts, which will be

related in the course of the work. I shall only add here, that it is

probable, that this sympathy does not depend on any communication of

nervous filaments, but on habit; owing to the various branches of this

system having frequently been stimulated into action at the same time.

There are a thousand instances of involuntary motions associated in this

manner; as in the act of vomiting, while the motions of the stomach and

oesophagus are inverted, the pulsations of the arterial system by a certain

sympathy become weaker; and when the bowels or kidneys are stimulated by

poison, a stone, or inflammation, into more violent action; the stomach and

oesophagus by sympathy invert their motions.

1. When any one drinks a moderate quantity of vinous spirit, the whole

system acts with more energy by consent with the stomach and intestines, as

is seen from the glow on the skin, and the increase of strength and

activity; but when a greater quantity of this inebriating material is

drank, at the same time that the lacteals are excited into greater action

to absorb it; it frequently happens, that the urinary branch of absorbents,

which is connected with the lacteals by many anastomoses, inverts its

motions, and a great quantity of pale unanimalized urine is discharged. By

this wise contrivance too much of an unnecessary fluid is prevented from

entering the circulation--This may be called the drunken diabetes, to

distinguish it from the other temporary diabetes, which occur in hysteric

diseases, and from continued fear or anxiety.

2. If this idle ingurgitation of too much vinous spirit be daily practised,

the urinary branch of absorbents at length gains an habit of inverting its

motions, whenever the lacteals are much stimulated; and the whole or a

great part of the chyle is thus daily carried to the bladder without

entering the circulation, and the body becomes emaciated. This is one kind

of chronic diabetes, and may be distinguished from the others by the taste

and appearance of the urine; which is sweet, and the colour of whey, and

may be termed the chyliferous diabetes.

3. Many children have a similar deposition of chyle in their urine, from

the irritation of worms in their intestines, which stimulating the mouths

of the lacteals into unnatural action, the urinary branch of the absorbents

becomes inverted, and carries part of the chyle to the bladder: part of the

chyle also has been carried to the iliac and lumbar glands, of which

instances are recorded by Haller, t. vii. 225. and which can be explained

on no other theory: but the dissections of the lymphatic system of the

human body, which have yet been published, are not sufficiently extensive

for our purpose; yet if we may reason from comparative anatomy, this

translation of chyle to the bladder is much illustrated by the account

given of this system of vessels in a turtle, by Mr. Hewson, who observed,

"That the lacteals near the root of the mesentery anastomose, so as to form

a net-work, from which several large branches go into some considerable

lymphatics lying near the spine; and which can be traced almost to the

anus, and particularly to the kidneys." Philos. Trans. v. 59. p.

199--Enquiries, p. 74.

4. At the same time that the urinary branch of absorbents, in the beginning

of diabetes, is excited into inverted action, the cellular branch is

excited by the sympathy above mentioned, into more energetic action; and

the fat, that was before deposited, is reabsorbed and thrown into the blood

vessels; where it floats, and was mistaken for chyle, till the late

experiments of the ingenious Mr. Hewson demonstrated it to be fat.

This appearance of what was mistaken for chyle in the blood, which was

drawn from these patients, and the obstructed liver, which very frequently

accompanies this disease, seems to have led Dr. Mead to suspect the

diabetes was owing to a defect of sanguification; and that the schirrosity

of the liver was the original cause of it: but as the schirrhus of the

liver is most frequently owing to the same causes, that produce the

diabetes and dropsies; namely, the great use of fermented liquors; there is

no wonder they should exist together, without being the consequence of each

other.

5. If the cutaneous branch of absorbents gains a habit of being excited

into stronger action, and imbibes greater quantities of moisture from the

atmosphere, at the same time that the urinary branch has its motions

inverted, another kind of diabetes is formed, which may be termed the

aqueous diabetes. In this diabetes the cutaneous absorbents frequently

imbibe an amazing quantity of atmospheric moisture; insomuch that there are

authentic histories, where many gallons a day, for many weeks together,

above the quantity that has been drank, have been discharged by urine.

Dr. Keil, in his Medicina Statica, found that he gained eighteen ounces

from the moist air of one night; and Dr. Percival affirms, that one of his

hands imbibed, after being well chafed, near an ounce and half of water, in

a quarter of an hour. (Transact. of the College, London, vol. ii. p. 102.)

Home's Medic. Facts, p. 2. sect. 3.

The pale urine in hysterical women, or which is produced by fear or

anxiety, is a temporary complaint of this kind; and it would in reality be

the same disease, if it was confirmed by habit.

6. The purging stools, and pale urine, occasioned by exposing the naked

body to cold air, or sprinkling it with cold water, originate from a

similar cause; for the mouths of the cutaneous lymphatics being suddenly

exposed to cold become torpid, and cease, or nearly cease, to act; whilst,

by the sympathy above described, not only the lymphatics of the bladder and

intestines cease also to absorb the more aqueous and saline part of the

fluids secreted into them; but it is probable that these lymphatics invert

their motions, and return the fluids, which were previously absorbed, into

the intestines and bladder. At the very instant that the body is exposed

naked to the cold air, an unusual movement is felt in the bowels; as is

experienced by boys going into the cold bath: this could not occur from an

obstruction of the perspirable matter, since there is not time, for that to

be returned to the bowels by the course of the circulation.