THE LYMPH AND THE CHYLE. 9 



very great numbers in the chyle obtained from the mesen- 

 teric and lymphatic glands : this observation has led to the 

 supposition that the white corpuscles are formed in those 

 glands. 



Upon this question, as upon so many others, Comparative 

 Anatomy throws much light. It has been ascertained that 

 the glands referred to have no existence in the amphibia and 

 in fislies ; in birds, too, they are only found in the neck. 

 Thus it is evident, that the lymphatic glands, however much 

 they may contribute to the formation of the white corpuscles, 

 are not essential to their production. 



Corpuscles, very analogous to those of the chyle and the 

 lymph, are found in vast quantities in the fluid of the 

 thymus gland in early life : these corpuscles Hewson con- 

 sidered to be identical with the globules of those fluids, and 

 therefore he regarded the thymus gland as an organ of nutri- 

 tion, and as an appendage to the lymphatic system. In this 

 opinion he has been followed by Mr. Gulliver. That it is 

 an organ of nutrition, adapted to the special exigencies of 

 early life, there can be no doubt ; but that it is an append- 

 age of the lymphatic system, and that the globules with 

 which it so abounds are the same as those of the lymph and 

 chyle, admits of much diversity of opinion. 



The globules of the thymus have undoubtedly striking 

 points of resemblance with the corpuscles so frequently al- 

 luded to ; they have the same granular structure ; they are, 

 like them, colourless, and to some extent they comport them- 

 selves similarly under the influence of certain re-agents. 



There are points, however, of dissimilarity as well as of 

 resemblance ; thus they are usually very much smaller than 

 the lymph corpuscles, they do not undergo any increase of 

 size when immersed in water, and acetic acid does not dis- 

 close the presence of nuclei. 



But above all, the corpuscles of the thymus differ from 

 those of the lymph and chyle in their situation : those of the 

 latter fluids are always inclosed in vessels in lymphatics, or 

 lacteal lymphatics ; while those of the former fluid, that of 

 the thymus gland, are extravascular, lying loosely in the 



