54 APPENDIX. 



the formation of carbonic gas, was very remarkably increased.* In a Negro, as far as we 

 could infer from experiments performed on a single limb, the respiratory function of 

 the external surface of the body was much greater, and the quantity of carbonic acid 

 formed in his lungs much less than in our own case although our size and weight were 

 equal. Hence we were led to infer that, in this race of the human species, the skin 

 performs a much greater supplementary function to that of the lungs, than in the in- 

 habitants of cold or temperate climates. 



In two cases which came under our observation, in which the lungs were partly de- 

 stroyed from an imposthume, and the side of the chest was consequently contracted, 

 the cutaneous functions were afterwards very remarkably increased. Were it consist- 

 ent with the limits of these notes, many facts illustrative of this particular function of 

 the skin, as it respects the inhabitants of cold, temperate, and hot climates, might be 

 adduced. 



2. The Skin is an Eliminating Organ. Richerand' has so fully illustrated this func- 

 tion of the skin, and contrasted it with that performed by the kidnies, that it is unneces- 

 sary to say any thing respecting it, at this place. The chemical analysis of the perspir- 

 ed fluid, given in the next chapter of the Appendix, will show to what extent it pep- 

 forms an eliminating office. 



Of tte Fluid? 

 Note AA. 



In .addition to the classifications of the fluids, we may mention that adopted by M. 

 Chaussier. He divides the fluids into five classes : those produced by the digestive 

 process the chyme and the chyle; the circulating fluids the lymph and the blood; 

 the exhaled or perspired humours; the follicular humours, and the glandular hu- 

 mours. 



M. Adelon, the able and eminent pupil of M. Chaussier, has proposed another classi- 

 fication, which possesses some advantages over those which have preceded it. It is 

 also simpler and more natural. He divides the organic fluids into those of Maorgtion, 

 the fluid especially Nutritive, and the Secreted Humours. 



1 The Absorbed Fluids are the chyle, the lymph, and the venous blood. These are 

 taken up and conveyed by the lymphatic and venous class of vessels, and ultimately 

 become assimilated with, and, indeed, concur to form the fluid specifically nutritive. 

 Thus the chyle, after a longer or shorter course, mingles with the lymph, both are 

 poured into the venous blood, and when they arive at the organs of respiration, they 

 become perfectly united, being converted into the nutritive fluid by the functions of 

 those organs. 



2 The Fluid especially Nutritive.- The three fluids constituting the first class being 

 changed in the respiratory organs into that which can alone nourish the body, thus 

 constitute the second class, which in its turn, furnishes the materials of all those em- 

 braced by the third. The second class is, therefore, the arterial blood only, which be- 

 ing fully perfected in the lungs by the action of the atmospheric air, and circulated 

 throughout the body, furnishes the materials of nutrition and secretion, and stimulates, 

 and contributes to preserve the functions of the living solids, and in conjuncton with 

 these solids,f produces the calorification of the animal system. 



3 The Secreted Humours This class may be divided into three orders, according to 

 the forms of the secreting organs which produce them ; namely, into Exhaled or Per- 

 spired Fluids, Follicular Humours, and Glandular Humours. 



Jl. Exhaled or Perspired Humours. These are numerous, are produced in the form 

 of vapour, and they differ from one another in their physical and chemical properties, 

 and in the purposes which they fulfil in the animal economy. They are, moreover, dis- 



* The experiments whidi were made in order to ascertain this from the want of the 

 means and proper facilities were not performed upon the whole body, they were made 

 only upon a single limb ; but the results were very decisive and remarkable. 



f By living solids is here meant all sensitive and irritable parts all those which are 

 influenced by an irritating cause. 



