ABSORPTION FROM THE BODY IN GENERAL. 515 



at the expiration of this period, the lymphatics were found full of milk, whilst 

 the veins contained none. In repeating this experiment upon a young man, 

 no milk could be detected in the blood drawn from a vein. It has been shown 

 by Muller that, when the posterior extremities of a Frog were kept for two 

 hours in a solution of prussiate of potass, the salt had freely penetrated the 

 lymphatics, but had not entered the veins. It does not follow, however, from 

 these and similar experiments, that in all tissues the lymphatics absorb more 

 readily than the veins ; for as the capillary blood-vessels in the lungs are much 

 more freely exposed to the surface of the air-cells, than are the lymphatics, 

 we should, on the principles just now stated, expect the former to 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. 



680. Our inferences with regard to the ordinary functions of the Lymphatic 

 system, however, must be rather drawn from the nature of the fluid which it 

 contains, and from the uses subsequently made of it, than from experiments 

 such as the preceding. We shall presently see, that there is a close corre- 

 spondence in composition between the Chyle of the Lacteals, and the Lymph 

 of the Lymphatics ; the chief difference being the presence in the former, of 

 a considerable quantity of fatty matter, and of a larger proportion of the as- 

 similable substances (albumen and fibrine) which are equally characteristic of 

 both ( 691). This evident conformity in the nature of the fluid which these 

 two sets of vessels transmit, 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 transmitted 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. On the other hand, 

 the close resemblance between the contents of the Lymphatics, and diluted 

 Liquor Sanguinis, seems to indicate that the former are partly derived from 

 the fluid portion of the Blood, which has transuded through the walls of the 

 Capillary vessels ; and we shall presently see reason to believe that this 

 transudation is for the purpose of subjecting certain crude materials, that have 

 been taken up direct into the blood-vessels, to an elaborating or preparatory 

 agency, which it seems to be the especial object of the Absorbent system to 

 exert upon certain of the nutritive components of the circulating fluid. 



681. But it seems not improbable that there may be another source for the 

 contents of the Lymphatics. We have already had to allude, on several oc- 

 casions, to the disintegration which is continually taking place within the living 

 body; whether as a result of the limited duration of the life of its component 

 parts, or as a consequence of the decomposing action of Oxygen. Now the 

 death of the tissues by no means involves their immediate and complete de- 

 struction ; and there seems no more reason why an animal should not derive 

 support from its own dead parts than from the dead body of another indi- 

 vidual. Whilst, therefore, the matter, which has undergone too complete a 

 disintegration to be again employed as nutrient material, is carried off by the 

 excreting processes that portion which is capable of being again assimilated, 

 may be taken up by the Lymphatic system. If this be the case, we may say, 

 with Dr. Prout, that " a sort of digestion is carried on in all parts of the body." 

 It may be stated, then, as a general proposition, that the function of the Ab- 

 sorbent System is to take up, and to convey into the Circulating apparatus, 

 such substances as are capable of appropriation to the nutritive process ; 

 whether these substances be directly furnished by the external world, or be 

 derived from the disintegration of the organism itself. We have seen that, 



