THYREOID GLAND OF THE TELEOSTS 735 



<!lear cytoplasm (pi. V, fig. 13, Coz), which may resemble 

 Hiirthle's colloid cells. The two types are probably different stages 

 in the same process. At times the cell body is broken up into 

 pieces before being transformed into colloid. The nucleus is 

 always destroyed last. 



A part of the colloid is therefore formed b}^ degenerating 

 epithehal cells which are either destroyed in their primary posi- 

 tion or after being pushed into the lumen. Anderson believes 

 that this is invariably the fate of the cells after several periods 

 of secretion. Hurthle, also, noticed this 'melting' of the epithe- 

 lium and was able to trace the complete disintegration of the 

 cytoplasm, though the fate of the nuclei remained doubtful. 

 They, too, are unquestionably destroyed within the colloid, 

 and as a matter of fact I could observe cell nuclei, such as those 

 of the red blood corpuscles, in all stages of disintegration, (pi. 

 V, fig. 13, N). L. Miiller regards the formation of colloid 

 material from disintegrated cells as of shght importance. Hurthle 

 remarks that in follicles of mammals with a flattened epithelium, 

 which he considers the final secreting stage, cell remnants or 

 defects in the wall can rarely be found. This is equally true in 

 Teleosts. 



I have never seen the signs of degeneration described by Maurer 

 in old carp. He records a sweHing of the epithelial cells which 

 breaks down the follicles, permitting lymphatic elements to enter 

 and form lymph nodules, similar to processes in Anura. Perhaps 

 my specimens were not old enough to show these phenomena. 



Pigment was not observed within the follicles, though outside 

 of them brown pigment is often found in the supporting tissue. 

 This is probably of haematogenic origin. Baber found brown 

 pigment granules within the colloid in the thyreoid gland of the 

 conger eel. I also fail to find crystals in the follicles or around 

 them as has been reported by some investigators. They are 

 undoubtedly postmortem products. 



In the conger eel Baber observed a reticulum between the 

 epithelial cells, in which they weie partially imbedded. He 

 states that this reticulum is formed by coagulated intercellular 

 substance and has nodal thickenings. At the thickened places 



