General Anatomy, Applied to Physiology and Medicine, Vol. 2 (of 3)

by Xavier Bichat

The mode of origin undoubtedly varies, but we do not know how it takes place. The exhalants are continued with their capillary net-work, in such a manner that we cannot say precisely where one finishes and the others begin. Hence why often in this work, in speaking of these small tubes, I suppose them to come immediately from the arteries, and forming the capillaries by their interlacing; this is evidently sufficient to understand what will be said hereafter.

II. Division of the Exhalants.

There are three classes of exhalants which I distinguish by the fluids or the substances they furnish.

The first class contains those that throw out the fluids not destined to enter the economy again; such are, 1st, the cutaneous exhalants that pour out the sweat; 2d, the mucous exhalants that furnish a part of the pulmonary perspiration, the greatest part being formed, as I shall say, by the dissolution of the mucous fluids of respiration, which yield perhaps the gastric, intestinal juices, &c.

In the second class are found the exhalants, that throw out fluids that remain for some time upon certain surfaces or in certain cells; and which afterwards taken up by absorption, re-enter the circulation through the lymphatics. These are, 1st, the serous exhalants which deposit upon their respective surfaces the serum which lubricates the membranes and facilitates the motions of the organs they cover; 2d, the cellular exhalants which pour out into the cells, on the one part serum, on the other fat; 3d, the medullary exhalants which carry into the middle of the bones the juices of the same name; 4th, the synovial exhalants which deposit the synovia, either upon the articulations, or in the tendinous grooves.

The third class contains the exhalants that carry to all the organs the nutritive substance that repairs them, and which is afterwards taken up by absorption, to be replaced by new substances.

I adopt in my course of physiology the division I have just pointed out, to explain the different exhalations, of which the last evidently leads me to speak of nutrition, a function which is the general end of those that form organic life. We can represent in the following table, all the different exhalations; it presents the assemblage of the organs that execute them.

EXHALANTS.
1st. exterior, open upon the systems,	1st. Dermoid.
	2d. Mucous.
2d. interior, open upon the systems,	1st Serous.
	2d. Cellular, where they pour out,	1st. Serum.
		2d. Fat.
	3d Medullary.	1st. of the short, flat bones, and the extremities of the long ones.
		2d. of the middle of the long bones.
	4th. Synovial.	1st. of the articulations.
		2d. of the tendons.
3d. nutritive.	Each organized texture has its own exhalants.

This is an accurate table of all the fluids that go out of the blood, without the intervention of the glands, and by the way of exhalation. The two first classes have vessels, as is accurately proved by experiment, observation and even inspection. As to the nutritive exhalants, there is no doubt but that new substances are continually carried to the organs to repair them; now it is necessary that these substances should have vessels; these vessels certainly cannot draw what they deposit in them, except from the capillary system in which they terminate. If injections or other means do not accurately prove the existence of these exhalants, it seems to me that this reasoning forces us to admit them.

Physiologists had not hitherto collected together all the exhalations; each was explained in treating of the system where it was found. I have thus given reflections upon each in the exposition of the different textures; the arrangement of the general anatomy required it; but in works or in lectures on physiology, they ought evidently to be presented under the same point of view as absorptions.