The _variety_ would now have replaced the _species_, of whic_Journal of the Proceedings of the Linnean Society

be a more perfectly developed and more highly organized form. It would

be in all respects better adapted to secure its safety, and to prolong

its individual existence and that of the race. Such a variety _could

not_ return to the original form; for that form is an inferior one, and

could never compete with it for existence. Granted, therefore, a

"tendency" to reproduce the original type of the species, still the

variety must ever remain preponderant in numbers, and under adverse

physical conditions _again alone survive_. But this new, improved, and

populous race might itself, in course of time, give rise to new

varieties, exhibiting several diverging modifications of form, any of

which, tending to increase the facilities for preserving existence,

must, by the same general law, in their turn become predominant. Here,

then, we have _progression and continued divergence_ deduced from the

general laws which regulate the existence of animals in a state of

nature, and from the undisputed fact that varieties do frequently occur.

It is not, however, contended that this result would be invariable; a

change of physical conditions in the district might at times materially

modify it, rendering the race which had been the most capable of

supporting existence under the former conditions now the least so, and

even causing the extinction of the newer and, for a time, superior race,

while the old or parent species and its first inferior varieties

continued to flourish. Variations in unimportant parts might also occur,

having no perceptible effect on the life-preserving powers; and the

varieties so furnished might run a course parallel with the parent

species, either giving rise to further variations or returning to the

former type. All we argue for is, that certain varieties have a tendency

to maintain their existence longer than the original species, and this

tendency must make itself felt; for though the doctrine of chances or

averages can never be trusted to on a limited scale, yet, if applied to

high numbers, the results come nearer to what theory demands, and, as we

approach to an infinity of examples, become strictly accurate. Now the

scale on which nature works is so vast--the numbers of individuals and

periods of time with which she deals approach so near to infinity, that

any cause, however slight, and however liable to be veiled and

counteracted by accidental circumstances, must in the end produce its

full legitimate results.

Let us now turn to domesticated animals, and inquire how varieties

produced among them are affected by the principles here enunciated. The

essential difference in the condition of wild and domestic animals is

this,--that among the former, their well-being and very existence depend

upon the full exercise and healthy condition of all their senses and

physical powers, whereas, among the latter, these are only partially

exercised, and in some cases are absolutely unused. A wild animal has to

search, and often to labour, for every mouthful of food--to exercise

sight, hearing, and smell in seeking it, and in avoiding dangers, in

procuring shelter from the inclemency of the seasons, and in providing

for the subsistence and safety of its offspring. There is no muscle of

its body that is not called into daily and hourly activity; there is no

sense or faculty that is not strengthened by continual exercise. The

domestic animal, on the other hand, has food provided for it, is

sheltered, and often confined, to guard it against the vicissitudes of

the seasons, is carefully secured from the attacks of its natural

enemies, and seldom even rears its young without human assistance. Half

of its senses and faculties are quite useless; and the other half are

but occasionally called into feeble exercise, while even its muscular

system is only irregularly called into action.

Now when a variety of such an animal occurs, having increased power or

capacity in any organ or sense, such increase is totally useless, is

never called into action, and may even exist without the animal ever

becoming aware of it. In the wild animal, on the contrary, all its

faculties and powers being brought into full action for the necessities

of existence, any increase becomes immediately available, is

strengthened by exercise, and must even slightly modify the food, the

habits, and the whole economy of the race. It creates as it were a new

animal, one of superior powers, and which will necessarily increase in

numbers and outlive those inferior to it.

Again, in the domesticated animal all variations have an equal chance of

continuance; and those which would decidedly render a wild animal unable

to compete with its fellows and continue its existence are no

disadvantage whatever in a state of domesticity. Our quickly fattening

pigs, short-legged sheep, pouter pigeons, and poodle dogs could never

have come into existence in a state of nature, because the very first

step towards such inferior forms would have led to the rapid extinction

of the race; still less could they now exist in competition with their

wild allies. The great speed but slight endurance of the race horse, the

unwieldy strength of the ploughman's team, would both be useless in a

state of nature. If turned wild on the pampas, such animals would

probably soon become extinct, or under favourable circumstances might

each lose those extreme qualities which would never be called into

action, and in a few generations would revert to a common type, which

must be that in which the various powers and faculties are so

proportioned to each other as to be best adapted to procure food and

secure safety,--that in which by the full exercise of every part of his

organization the animal can alone continue to live. Domestic varieties,

when turned wild, _must_ return to something near the type of the

original wild stock, _or become altogether extinct_.

We see, then, that no inferences as to varieties in a state of nature

can be deduced from the observation of those occurring among domestic

animals. The two are so much opposed to each other in every circumstance

of their existence, that what applies to the one is almost sure not to

apply to the other. Domestic animals are abnormal, irregular,

artificial; they are subject to varieties which never occur and never

can occur in a state of nature: their very existence depends altogether

on human care; so far are many of them removed from that just proportion

of faculties, that true balance of organization, by means of which alone

an animal left to its own resources can preserve its existence and

continue its race.

The hypothesis of Lamarck--that progressive changes in species have been

produced by the attempts of animals to increase the development of their

own organs, and thus modify their structure and habits--has been

repeatedly and easily refuted by all writers on the subject of varieties

and species, and it seems to have been considered that when this was

done the whole question has been finally settled; but the view here

developed renders such an hypothesis quite unnecessary, by showing that

similar results must be produced by the action of principles constantly

at work in nature. The powerful retractile talons of the falcon- and the

cat-tribes have not been produced or increased by the volition of those

animals; but among the different varieties which occurred in the earlier

and less highly organized forms of these groups, _those always survived

longest which had the greatest facilities for seizing their prey_.

Neither did the giraffe acquire its long neck by desiring to reach the

foliage of the more lofty shrubs, and constantly stretching its neck for

the purpose, but because any varieties which occurred among its

antitypes with a longer neck than usual _at once secured a fresh range

of pasture over the same ground as their shorter-necked companions, and

on the first scarcity of food were thereby enabled to outlive them_.

Even the peculiar colours of many animals, especially insects, so

closely resembling the soil or the leaves or the trunks on which they

habitually reside, are explained on the same principle; for though in

the course of ages varieties of many tints may have occurred, _yet those

races having colours best adapted to concealment from their enemies

would inevitably survive the longest_. We have also here an acting cause

to account for that balance so often observed in nature,--a deficiency

in one set of organs always being compensated by an increased

development of some others--powerful wings accompanying weak feet, or

great velocity making up for the absence of defensive weapons; for it

has been shown that all varieties in which an unbalanced deficiency

occurred could not long continue their existence. The action of this

principle is exactly like that of the centrifugal governor of the steam

engine, which checks and corrects any irregularities almost before they

become evident; and in like manner no unbalanced deficiency in the

animal kingdom can ever reach any conspicuous magnitude, because it

would make itself felt at the very first step, by rendering existence

difficult and extinction almost sure soon to follow. An origin such as

is here advocated will also agree with the peculiar character of the

modifications of form and structure which obtain in organized

beings--the many lines of divergence from a central type, the increasing

efficiency and power of a particular organ through a succession of

allied species, and the remarkable persistence of unimportant parts such

as colour, texture of plumage and hair, form of horns or crests, through

a series of species differing considerably in more essential characters.

It also furnishes us with a reason for that "more specialized structure"

which Professor Owen states to be a characteristic of recent compared

with extinct forms, and which would evidently be the result of the

progressive modification of any organ applied to a special purpose in

the animal economy.

We believe we have now shown that there is a tendency in nature to the

continued progression of certain classes of _varieties_ further and

further from the original type--a progression to which there appears no

reason to assign any definite limits--and that the same principle which

produces this result in a state of nature will also explain why domestic

varieties have a tendency to revert to the original type. This

progression, by minute steps, in various directions, but always checked

and balanced by the necessary conditions, subject to which alone

existence can be preserved, may, it is believed, be followed out so as

to agree with all the phenomena presented by organized beings, their

extinction and succession in past ages, and all the extraordinary

modifications of form, instinct, and habits which they exhibit.

Ternate, February, 1858.

FOOTNOTES:

[A] This MS. work was never intended for publication, and therefore was

not written with care.--C. D. 1858.

[B] I can see no more difficulty in this, than in the planter improving

his varieties of the cotton plant.--C. D. 1858.

Contributions to the Anatomy and Natural History of the Cetacea. By R.

KNOX, Esq., M.D., F.R.S.E. Communicated by the Secretary.

[Received Oct. 6, 1857.]

Part I. THE DOLPHINS.

The dissection of the Cetacea, and more especially of the larger kinds,

is attended with great difficulty, and not unfrequently entails heavy

expenses on those who attempt it. For these reasons I have thought that

zoologists might be pleased to have, even now, submitted to them the

results of numerous dissections made many years ago, when, not stinted

in means, and having the aid of excellent assistants, I attempted the

dissection even of the gigantic Arctic Rorqual, the largest, perhaps, of

all living beings. Certain of the details have been from time to time

laid before the public, but in an extremely scattered and incomplete

form, and without the illustrations (artistic), which explain so much

better than any verbal description. The greater part is still before me

in manuscript. It is my intention in the following contributions to

endeavour to connect them together, adding to those already published

many facts I find in MSS. The original drawings, made by my brother and

by Messrs. Edward Forbes and Henry Goodsir (who were at that time my

students and assistants), are still in my possession.

_Determination of Species._--The determination of species as regards the

_Cetacea_ is one of much difficulty; Cuvier met this difficulty by an

appeal to anatomy. The number of vertebræ composing the vertebral column

(exclusive of the cephalic) seemed to me a tolerably secure guide in the

determination of species,--being aware, however, that some doubted the

method, believing that the number of the vertebræ might vary, first,

with the individual, secondly with the age of the specimen. I still

continue to be of my original opinion, that the number of vertebræ

comprising the vertebral column, properly so called, may safely be

trusted in determining the species of the Cetacea; and with this view I

drew up the following Table, excepting from it the genus _Dugong_, which

I have never considered to be a Cetacean:--

_Tabular View of the Number of the Vertebræ in certain Cetacea._

(Cephalic vertebræ excluded.)

---------------------------------------------------------------------

| Authorities. |

| ---------------------------------------------------

| SPECIES. | CUVIER. RUDOLPHI. KNOX. J. HUNTER. HUNTER |

| | (Glasgow.)|

---------------------------------------------------------------------

| | | | | | |

|Greenland | | | 48 | | |

| | | | | | |

| | | | | | |

|Seas | 59 | | | | |

| | | | | | |

|Rorqual | | | 65 | | |

| | | | | | |

|by Rudolphi | | 54 | | | |

| | | | | | |

|Rorqual | | | | | 48 |

| | | | | | |

|not stated | | | | | 61 or 62. |

| | | | | | |

|North | | | 48 | 46 | 46 |

| | | | | | |

|the Cape | 52 | | | | |

| | | | | | |

|Cachalot | 60 | | | | |

| | | | | | |

|_D. Delphis_ | 67 | | | | |

| | | | | | |

|my museum | | | 81 | | |

| | | | | | |

|Glasgow | | | | | 90 |

| | | | | | |

|Hunter | | | | 60 | |

| | | | | | |

|_D. Phocæna_ | 66 | | 65 | 51 | |

| | | | | | |

|Beneden | | | | | 90 |

---------------------------------------------------------------------

In a late number of the 'Bulletins of the Royal Academy of Brussels' I

find some valuable remarks in respect of these points by M. Van Beneden.

He praises, and deservedly, no doubt, the exertions of M. Eschricht to

collect a proper Museum of the Cetacea. It appears, according to M.

Eschricht, that at no age whatever do we find in true whales (meaning, I

presume, the _Mysticetus borealis_ and _australis_) any distinct

vertebræ in the cervical region as in other mammals. A fusion of all

into one bone or cartilage seems to take place even in the youngest

foetus. In the foetus examined by me of this species (a specimen removed

from the uterus of a true _Mysticetus_ killed in the Greenland seas), I

do not recollect the precise appearance of the cervical vertebræ; but

the skeleton is in existence, and shall be referred to. To the skeleton

of the Rorqual now in the Museum at Antwerp, and which seems to me of

the same species as the one I dissected in Scotland (and of which the

skeleton, prepared with infinite care by my brother and myself, was

presented by me to the Town Council of Edinburgh, and is now preserved

in the Zoological Gardens of the same city), he gives the following

vertebræ:--

Skeleton of the Rorqual at Antwerp--Cervical 7

Dorsal 14-15

Lumbar 15

Caudal 25[C]

--------

Total 61 or 62

In the skeleton of the Great Rorqual now in the Zoological Gardens at

Edinburgh, and originally dissected and prepared by my brother and

myself, these vertebræ are--

Cervical 7

Dorsal 15

Lumbar and Caudal 43

Total 65

In that of the Lesser Rorqual I dissected in 1830, the skeleton of which

I think is still preserved in the Museum of the University of Edinburgh,

we found--

Vertebræ.

Cervical 7

Dorsal 11

Lumbar 13

Caudal 17

Total 48

The specimen was that of a young animal, and of the same species, I

believe, as the one described by Mr. Hunter and Fabricius; it is a

distinct species, and not merely the young of the Great Rorqual.

I shall return to the Dugong, as not being a Cetacean, in a future

Section: its skeleton has been examined in a masterly way by De

Blainville, an anatomist and observer of the highest order, since the

time I wrote and published my Memoir on the Dugong.

The first great step in the anatomy of the Cetacea is unquestionably due

to Cuvier; but his dissections were almost confined to the genus

_Delphinus_, or the common Porpoise of our coasts. I repeated all his

dissections, and found them, as they almost always were, scrupulously

exact; but when I came to examine Cetacea with whalebone instead of

teeth, I was surprised to find how different, in fact, the anatomy of

the two great families was. Scarcely in any great natural family do we

find Cuvier's favourite theory of anatomical and physiological

co-relations so entirely at fault as in the Cetacea. The teeth or

whalebone, as natural-history characters, lead to no results; the whole

structure of the interior defies all _à-priori_ reasoning. The brain in

whalebone-whales does not fill the interior of the cranium; so that the

capacity of the one is no measure of the solid bulk of the other. Their

food is various, having no relation to the teeth or buccal appendages;

vascular structures surround the spinal marrow, and extend in the

_Balænopteræ_ into the cavity of the cranium, which seem to be without

any analogy in other mammals, or, at the least, a very obscure one, and

whose functions are wholly unknown.

Cetacea might with some propriety be divided into whales with whalebone,

and whales with teeth. Those with whalebone have rudimentary teeth in

both jaws in the foetal state. Fossil Cetacea exist, and they seem to

have been of both kinds, but, no doubt, were generically and

specifically distinct from the recent. Judging from the remains of those

I have seen, I am inclined to think that those with teeth were of a

stronger and firmer build in the skeleton than those called recent; that

the neck was longer, and the caudal portion of the column shorter than

in the recent kinds, and that they approached the Saurians in form.

There is a remarkable want of symmetry in the crania of some of the

Cetacea; but most remarkable is the cranium of the Narwhal. Of this fact

I have already spoken, in the article published in the Transactions of

the Royal Society of Edinburgh.

_Delphinus Phocæna. Dissection of a small Cetacean sent to me from

Orkney in the month of May 1835._--This species is said to abound on the

coasts, and to furnish a kind of fishery to the inhabitants. On

dissection we found 81 vertebræ, exclusive of the cephalic. The species

must be quite distinct from those previously and subsequently examined

by myself and many others, in which the number of vertebræ ranged from

61 to 66. It is also, I think, distinct from the specimen I saw in Dr.

R. Hunter's Museum in Glasgow, in which the number of vertebræ was 90,

exclusive of the cephalic in all the cases. Thus it stands with regard

to the Cetacea called Porpoises and Dolphins.

In certain species of _Delphinus_ the vertical column is composed of 61

vertebræ, in others of 65, in others of 66, in others of 81, in others

of 90.

The specimen I now describe was, no doubt, that of a young animal; and

the skeleton was prepared, consequently, as a natural one. This method

has the advantage of security against the loss of any important osseous

structures, which too frequently happens when the bones require to be

macerated. The bones contained little oil, and weighed, head included,

only 7-1/4 lbs.; the whole animal, when entire, weighed 14 stone, or 196

lbs.; the skeleton therefore was about a twenty-fourth part of the whole

weight. It was a female. The external nostrils terminated in a single

orifice of a semilunar shape, with the concavity turned towards the

snout. Measurements of young animals have not the importance of those of

the adult; but I give them here because I think that the specimen,

although young, had nearly attained its full growth:--

ft. in.

Total length over the dorsum 6 5-2/8

Total length lateral surface 6 11-2/8

Total length abdominal surface 6 11-2/8

From the snout to the nostrils 0 11-4/8

From the nostrils to the dorsal fin 1 6-4/8

Base of the dorsal fin 0 11

From dorsal fin to foot of tail 3 0-2/8

Breadth of pectoral limb 0 4-4/8

From the snout to the organs of generation 3 9-4/8

Circumference anterior to the arm 2 9

Circumference anterior to dorsal fin 3 2-4/8

Circumference posterior to dorsal fin 2 10

Circumference at setting on of the tail 0 8-4/8

Length of pectoral limb 0 10

Breadth of tail 1 2

Greatest height of the dorsal fin 0 9

From the notes taken at the time, I find that my brother remarks that

the Dolphin of Orkney differed a good deal in shape from those found in

the Forth and seas in the South of Scotland. There were, moreover, 16

more vertebræ than in the skeleton of the Common Porpoise of authors.

The teeth generally weighed 2-1/2 grains each.

Further, the muscles of the tongue, intrinsic as well as extrinsic, were

extremely well developed. The isthmus faucium was 3 inches long. All

this part was extremely glandular. A well-marked muscular gullet

followed, composed of two layers of muscular fibres,--one circular

internally, and one longitudinal externally. These latter sent a slip to

the base of the arytænoid cartilages. The mucous membrane of the gullet

had no true epidermic covering, and in this respect differed remarkably

from the first gastric compartment, from which a cuticular lining could

be peeled off, as strong as that from the sole of the foot in man. The

larynx presented that organization so well described by the illustrious

Cuvier, and which I believe to be peculiar to the whales with teeth. It

differs very much, as I explained long ago, in its arrangement from that

of Whalebone Whales,--a fact of which I think Cuvier was not aware. The

cricoid cartilage was imperfect in form; the hyo-epiglottic muscles very

strong. The proper arytænoid were present, and strong, but did not

extend so high as in man; the thyro-arytænoid muscles were very fully

developed. In the interior of the larynx there were no projections nor

ventricles, no cuneiform cartilages, nor cornicula laryngis. The rings

of the trachea formed complete circles.

_Stomach._--The cuticular lining is limited to the first cavity or

compartment. It is in the second compartment that is found the curious

glandular arrangement first, I believe, described by me in the

'Transactions of the Royal Society of Edinburgh.' This structure is most

probably not limited to the second compartment. There are four distinct

compartments in the stomach of this animal. A dilated duodenum follows,

6 inches in length. It is possible that this may have been in some

instances mistaken for a stomach. The valvulæ conniventes commence with

the jejunum; these are longitudinal, and extend to within about 6 inches

of the anus, terminating at a point where the intestine seems enlarged.

The length of the intestines, large and small, was 90 feet;

circumference generally about 2 inches. Thousands and tens of thousands

of parasitical worms were found in the stomach, but none in the

intestine. In the stomach also we found four mandibles of the

cuttlefish, but no remains of anything in the intestines, and no

parasites.

_Heart and Vessels._--The heart weighed exactly one pound. The

Eustachian valve was small, that of Thebesius imperfect. The aorta

proceeded for about 3 inches of its course before giving off any

branches. At a point corresponding to the 15th or 16th lumbar vertebra

the vessel divided into the common iliacs. The _art. sacri media_, its

continuation, continued its course protected by the V-bones, and giving

off branches corresponding to the intervertebral spaces.

_Brain and Nervous System._--The erectile tissue surrounding the spinal

cord and origin of the spinal nerves in the Cetacea did not extend into

the interior of the cranium. The entire encephalic mass weighed 2-1/2

lbs.: cerebrum, 2 lbs.; cerebellum, 1/4; pons and medulla, 1/4 = 2-1/2.

Compared with a drawing of Camper of the _Delphinus Phocæna_, the brain

was found to differ remarkably, in being much broader in the line of the

middle and posterior lobes. In no animal did I ever find the fibrous

structure of the brain so well marked; and this extended to the

cerebellum[D]. I give here some measurements of the brain, which may be

of use to future observers. The brain is short from before backwards,

but broad transversely:--

Antero-posterior diameter 5-2/8 inches.

Breadth 8 inches.

Greatest breadth of the cerebellum 4 inches.

Length of the cerebellar hemisphere 4-6/8 inches.

Depth of ditto 3-2/8 inches.

Weight of the encephalic mass 2-1/2 lbs.

Depth of the interhemispherical fissure 1-2/8 inches.

Length of the corpus callosum 1-7/8 inches.

Weight of cerebrum 2 }

Weight of cerebellum 0-1/4} = 2-1/2 lbs.

Weight of the pons and med. oblongata 0-1/4}

_Nerves._--The 7th pair was found to be unexpectedly large and firm,

including both portions. The anterior roots of the spinal nerves were

far more numerous than the posterior or dorsal.

_Muscles._--The panniculus carnosus, strong and fleshy, extended nearly

over the whole trunk. The recti abdominis were powerful, and attached

inferiorly in this way:--A portion runs to the pelvic bones; a much

stronger to a strong aponeurosis, situated between the anus and the root

of the tail.

Journal of the Proceedings of the Linnean Society - Vol. 3 Zoology · 第 6 / 21 段

The _variety_ would now have replaced the _species_, of which it would