ABSORPTION BY THE GENERAL SURFACE. 351 



absorb more readily. This appears from experiment to be the fact ; for, when 

 a solution of prussiate of potass was injected by Mayer into the lungs, the salt 

 could be detected in the serum of the blood much sooner than in the lymph, 

 and in the blood of the left cavities of the heart, before it had reached that of 

 the right. 



467. It is not, however, from the external world alone, that Animals derive 

 the materials of their Nutrition. It has been stated ( 84) that the necessity 

 for a constant supply of food, arises from the continual decomposition which is 

 taking place within the living body ; and it will be hereafter shown that this 

 decomposition is connected with the death of the cells, of which the several 

 parts are constructed, these having an independent life of their own, and con- 

 sequently a limited duration, which has no immediate connection with that of 

 the organism at large ( 646). In every portion of the body, therefore, mate- 

 rials for nutrition are continually being set free ; and we find a peculiar pro- 

 vision for the re-introduction of these into the circulating fluid. All animals 

 which have a lacteal system have also a lymphatic system, closely correspond- 

 ing to it in aspect, but consisting of vessels that are distributed through the 

 whole body, instead of on the intestinal surface only, permeating almost every 

 tissue, and in many forming a most minute plexus. These vessels pass, like 

 the lacteals, through conglobate glands, in which they are brought into inti- 

 mate relation with blood-vessels ; and they empty their contents into the same 

 receptacle, so as to pour them into the blood in precisely the same manner. 

 The evident conformity in the nature of the fluid which these two sets trans- 

 mit, joined to the fact of the fluid Lymph, like the Chyle, being conveyed 

 into the general current of the circulation just before the blood is again trans- 

 mitted to the system at large, almost inevitably leads to the inference, that 

 the lymph is, like the chyle, a nutritious fluid, and is not of an excrementitious 

 character, as formerly supposed. The following is the most recent compara- 

 tive analysis of the two, as performed by Dr. G. O. Rees ; the fluids were 

 procured from the lacteal and lymphatic vessels of a donkey, previously to 

 their entrance into the thoracic duct ; the animal was killed seven hours after 

 a full meal. 



Chyle. Lymph. 



Water 90-237 98-536 



Albuminous matter - 3-516 1-200 



Fibrinous matter 0-370 0-120 



Animal extractive matter, soluble in water and alcohol 0-332 0-240 



Animal extractive matter, soluble in water only 1-233 1-319 



Fatty matter - 3-601 a trace 



Salts ; Alkaline chloride, sulphate and carbonate, with > n-711 0-585 

 traces of alkaline phosphate, oxide of iron 5 



100-00 100-00 



From this analysis it appears that the chief chemical difference between the 

 chyle and lymph consists in a much larger proportion of assimilable sub- 

 stances, albumen, fibrin, and fatty matter, contained in the former: the 

 nature and amount of the less clearly-defined animal principles, and of the 

 saline ingredients, appear to be nearly identical in both. 



468. Hence it can scarcely be doubted that, to use Dr. Prout's expression, 

 " a sort of digestion is carried on in all parts of the body ;" and that such of 

 the products of that digestion as are fit to be again converted into organized 

 tiss.ue, are re-introduced into the current of the circulation by the Lymphatics ; 

 whilst those which have undergone too great a degree of decomposition, are 

 carried off by the Excreting processes. In this way, Animals, when deprived 



