212 E. CRESSWKI.L BABEK. 



it is further important to bear in mind that the material in 

 the lymphatics completely fills and even distends the vessels, 

 without containing any formed corpuscles ; the material 

 cannot, therefore, be lymph. Hence it is reasonable to think 

 that one, possibly the chief, functioti of the thyroid gland 

 is the formation, within the vesicles, of a material which is 

 transferred from these by the lymphatics to the general cir- 

 culation, there to serve some purpose in the animal economy 

 as yet unknown. The close relationship existing between 

 the lymphatic tubes and the walls of the vesicles, together 

 with the abundant distribution of lymphatics, both within 

 and without the gland, appear to lend support to this 

 view. 



Frey {op. cit., p. 232), speaking of the glands formed of 

 closed vesicles, mentions this theory, and alludes to it as " a 

 very insufficient explanation." He may well do so, seeing 

 that he gives no reason in support of it ; for neither Frey, nor 

 any other author I have consulted, alludes to the contents of 

 the lymphatics, still less to the identity {morphological, at 

 least) existing between the contents of the vesicles (where the 

 material is supposed to be formed) and those of the lympha- 

 tics (by which it is supposed to be carried off) ; nor do they 

 give any other ground in support of this view. 



Note. — May, 1877. — In addition to the above structures 

 in the thyroid gland of the dog, bodies of considerable size 

 are frequently seen, usually on the surface, which differ 

 greatly in structure from the rest of the gland. From a com- 

 parison of their structure with that of the gland in tiie 

 embryo, I am led to believe that they are probably portions of 

 the organ whose development has been arrested before the 

 formation of vesicles has taken place. It will suffice to 

 mention these bodies here, leaving a description of them to a 

 future time. 



