205 



llant and red the colour of the blood, the greater the proportion of the 

 fibrous part. The pale, aqueous, and colourless blood of a dropsical 

 patient contains very little fibrina. In putrid or adynamic fever, in which 

 bleeding, as is universally known, is improper, I have sometimes seen the 

 blood containing but a small portion of fibrina, and very slow of coagu- 

 lating: its texture seemed to suffer from the affection under which the 

 muscular organs were evidently labouring. In inflammatory diseases, 

 on the contraryyRhe plastic power cf the blood is augmented; the fibrina 

 is in greater quantity, even the albumen coagulates spontaneously, and 

 forms a crust above the serum, which is always in smaller quantity*. 



XCIL Of the changes on the blood. The fluids not only undergo changes 

 in their composition, in their qualities and nature, when the action of the 

 solids is itself altered ; but even the absorbent system may introduce into 

 the mass of our fluids, heterogeneous principles, evidently the cause of 

 several diseases. In this manner, all contagions spread; the virus of 

 small-pox, of syphilis, of the plague, Sec. Thus, in time, the habitual 

 use of the same aliment produces in our fluids a crasis or peculiar consti- 

 tution, which has, on organized solids, an influence acting even on the 

 mindf. 



A purely vegetable diet conveys into the blood, according to Pythago- 

 ras, bland and mild principles: this fluid excites the organs in a mode- 



* According 1 to Mr. BRA^DB and Sir E. Hoiwt, both venous and arterial blood contain 

 carbonic acid in the proportion of two cubic inches of the gas for each ounce of blood. 

 This acid disengages itself immediately, when a portion of the warm blood is placed in 

 an air-pump. See APPENDIX, Note B B, for farther remarks respecting 1 the blood. 

 Copland. 



j- These opinions of our author are evidently borrowed fronx.the humoural pathology. 

 Of this system, much is still retained, and especially by me French pathologists. We 

 believe that the changes wrought in the fluids are wholly produced through the inter- 

 vention of the solids. Not thellightest proof exists of their being vitiated by the intro- 

 duction of ' heterogeneous principles," much less, that the mixture is the "cause of 

 several diseases." It is manifest, that every portion of the absorbent system has the 

 power, in a very great degree, of digesting and animalizing the substances which are 

 taken up. This property of the absorbents is a provision of nature, to prevent noxious 

 substances from penetrating into the circulation unchanged. In most instances, they 

 are fully adequate to this end. Where they are not, the substance passes to the firs't 

 lymphatic gland, which takes on inflammation and intercepts its further progress, as in 

 the case of bubo. In this respect, therefore, the conglobate glands may be considered 

 as sentinels guarding the exterior approaches of the body. 



We are not ignorant that some of the properties of certain substances, when absorbed, 

 display themselves in the secretions and excretions, as the odour of garlic, the colouring 

 matter of madder, &c. &c. But it does not hence follow, that they entered the circu- 

 lation unchanged. 



Experiments, indeed, prove quite the contrary, as neither one nor the other can be 

 detected in the serum of the blood. It seems to us most probable, that the process of 

 assimilation, whether performed by the chylopoietic viscera, or by the absorbent appa- 

 ratus, completely decomposes all substances subjected to its influence, and, however 

 various in their principles, reduces them to one 'homogeneous fluid, bland and inope- 

 rative in its nature, or in other words renders it fit for the purpose of nutrition. But, 

 in the excretions or secretions, being removed beyond the sphere of the vital powers, 

 chemical action takes place, by which those substances are in part or entirely regene- 

 rated. 



Whether the particular explanation offered by this hypothesis be received or not, the 

 fact at least must be acknowledged, that no substance in its active condition does enter 

 into the circulation, since experiments have shown, that however mild the fluid may be, 

 either milk or mucilage, oil or pus, it cannot even in the smallest quantity be injected 

 directly into the blood vessels without occasioning the most fatal consequences. As 

 regards the operation of substances on the Jiving system, we do not think it at all ne 



