THYREOID GLAND OF THE TELEOSTS 731 



with the blood and lymph capillaries. The process cells are limited 

 in number and he close together. Their cell body is swollen with 

 foamy cytoplasm containing several deeply stained highly refrac- 

 tive granules. Perhaps these cells are in a state of degeneration, 

 probably colloidization, although their plasma does not show any 

 acidophilia (pi. IV, fig. 5, E). Peremeschko observes somewhat 

 comparable features in the thyreoid glands of birds and mammals, 

 especially in that of the rabbit. Some of the epithelial cells possess 

 at their basal end from one to ten small projections, and thus 

 resemble the tassel cells Pfiuger has described in salivary glands, 

 except that in the thyreoids the processes are shorter. In some 

 cases Peremeschko found such cells in fresh material and could 

 isolate these follicles, which appear to be surrounded by a fringe. 

 Pfliiger regarded the cell processes as nervous, but Peremeschko 

 correctly believes them to come from the cytoplasm of the epi- 

 thelial cells. 



The function of the follicles can be much more easily studied in 

 other groups of vertebrates than the teleosts. In dissecting out 

 the follicles, as far as they are macroscopically visible, and fixing 

 them, it is almost impossible to avoid destroying the finer struc- 

 tures. Hemorrhages are almost unavoidable in cutting open the 

 gill region. On the other hand, in fixing the entire floor of the 

 pharynx the fixation fluid does not penetrate sufficiently fast to 

 preserve the finest details, and the general structures are unfavor- 

 ably influenced by the decalcification process. Microchemically, 

 therefore, little can be done and I limit myself to what could be 

 determined from studies of general structures. 



Hiirthle's colloid cells were seldom seen in the thousands of 

 follicles observed. Whether they are not generally formed, or 

 whether they appear and are emptied in so short a time as to be 

 rarely preserved I am unable to say. In Clupea (pi. V, fig. 20, 

 Coz.) they were hmited to four or five neighboring follicles and 

 in these all of the epithelial cells were so swollen that in some cases 

 they met in the center of the follicle, obhterating the lumen. The 

 nuclei were compact and deeply staining and occurred directly 

 under the free surface of the cell. The cytoplasm was homogeneous, 

 highly eosinophile, and sharply distinguished from that of other 



