The colour of these glands, reddish in childhood, grey in the adult,
becomes of a yellowish tinge in old age, and has that subsidence and
flaccidity which then characterize almost all the organs. This colour
varies also according to the regions; thus the bronchial glands have
a black appearance, inherent in part in their structure, but owing
probably also to the fluid that they contain, as the appearance of this
fluid proves, when it is pressed out of a divided gland. This colour
does not depend on its proximity to the lungs and on their colour,
though we know, they have many black spots upon them; the proof of this
is, that I have already very often found the lumbar, mesenteric glands,
&c. also black. Yet there is no part in which this colour would be
more common than around the lungs. Cruikshank, in order to prove the
passage of the lymphatics through the glands, says that he has found
those in the neighbourhood of the liver yellow in jaundice, in which
it is very probable that there is absorption of bile. But this remark
is unimportant, since all the parts of the body, without exception,
exhibit, in this affection, this colour, which is only a little more
evident in the cellular parts.
We cannot deny however but that these glands often take a colour
similar to that of the fluid which fills the absorbents, either in a
natural state, or in injections, on account of the great number of
vascular divisions that penetrate them internally. During digestion, at
the moment the lacteals are transmitting chyle, the mesenteric vessels
become almost as white as this fluid, and soon lose this colour when
the transmission is finished. By filling the absorbent system with
mercury, the same phenomenon is observed.
_Common Parts._
The structure of the lymphatic glands, considered in its common parts,
is as follows; a very abundant, extensible, loose cellular texture
surrounds them, allows them to be moved and easily displaced by the
finger when pushed against them. Hence the remarkable mobility of most
of these organs, in the first periods of their swelling; in which this
texture does not then participate; for it is gradually affected, loses
its laxity, and then adhesion succeeds to mobility. Thus in cancer,
the glands are first rolling, and afterwards become fixed. In acute
inflammations, they are in general fixed, because the neighbouring
texture partakes almost always of the disease.
The cellular texture forms besides around the glands a thick membrane
which more immediately envelops them, and which deprived of fat and
serum, exhibits the nature of the cellular covering of the absorbents.
It is this last membrane which, in the ordinary state, gives to the
glands an appearance in general smooth and polished; for mercurial
injections develop in them some roughness, owing to the prominence
of the vessels that run through them in the interior. Some slight
depressions are also visible on their surface; they are to these
glands, what the furrows on their concave face, are to the liver,
the spleen and the lungs; it is through them that the vessels enter.
We might think that the arteries were very numerous in the lymphatic
glands, if we judged from injections which colour the whole of them,
if they are fine and adroitly used; but little reliance should be
placed upon this. Simple inspection, in a living animal, which is
infinitely more certain, does not discover much blood in these glands.
In the fœtus and in childhood, the quantity of this fluid is much more
considerable; hence in part the redness that characterizes these organs
at this period of life. We are ignorant whether nerves exist in them,
and whether any of the numerous branches that the ganglions send in
their neighbourhood, especially in the mesentery, are introduced into
their texture; I have never traced any of them there.
_Peculiar Texture._
The peculiar substance of the lymphatic glands exhibits a pulp
very analogous to that of the nervous ganglions. No fibre can be
distinguished in them. Soft in the fœtus, withered in the few glands
that remain in old age, this substance, is particularly altered, as
I shall say, by scrophulous diseases, and by the influence of the
affections of the neighbouring organs.
This peculiar texture has a greater or less density. We find it more
solid, and resisting better the injection of mercury in the superficial
glands than in the deep-seated. They have cells at short distances,
especially in childhood; they contain a whitish fluid, which disappears
as well as the cells themselves, at an advanced age. This fluid, of a
very peculiar nature, can only be compared with those of the thyroid
and thymus glands, which, like this, are found as it were extravasated,
in the interstices of the organs that separate them, they have no
reservoirs, and their use is wholly unknown. There is no doubt that the
great quantity of blood that enters the lymphatic glands in childhood,
is owing to the superabundance of this fluid. Sometimes in the adult,
there is a great quantity of it in the bronchial glands, where it
is of a blackish colour. Some physiologists have thought, without
anatomical proof, that it is spread out upon the bronchiæ, and that
it forms in part the black spittle that is thrown out in the morning.
Fourcroy in particular is of this opinion; he attaches importance to
the black colour of these glands, which are perhaps, according to him,
the reservoir of the carbonaceous matter of the blood. The fact is,
they belong to the lymphatic system; that in a great number of subjects
they are grey or red; that we do not know that they have an excretory;
that their texture is pulpy like that of the analogous glands; and that
their size distinguishes them however from all others. I have observed
that the acids, the alkalis and stewing, alter but little their black
colour and that of the fluid contained in them.
It is in the peculiar texture of the lymphatic glands that the
absorbents ramify, after being introduced there in a certain number,
and each with numerous ramifications, and afterwards go out by many
other branches which also give rise to an infinity of smaller ones.
Each gland may in this respect be considered as the centre of two
small opposite capillary systems, which anastomose with each other.
In the interior of these glands, these branches very tortuous, folded
upon themselves in different ways, occupy a great part of the peculiar
texture of these organs which many thought in consequence were nothing
but an interlacing of the absorbents; an idea that is not proved, since
this texture is not yet well known.
I have observed that it is susceptible of less horny hardening than
most of the other animal textures. It approximates in this respect that
of the true glands; but it differs in this, that instead of continuing
to harden by long continued boiling, it soon softens, becomes pulpy,
and breaks with great ease under the finger. The acids after having
crisped it, dissolve it also more easily than many of the other
textures; the sulphuric and muriatic are remarkable for this. Exposed
to the action of the alkalis, it loses some of its principles, which
weaken these menstrua; but it is never entirely dissolved.