736 J. F. GUDERNATSCH 



the 'club shaped' cells described above are located and may be 

 clearlj^ distinguished from the ordinary epithelial cells. I did 

 not find such a reticulum, and it is possible that the filling of 

 the intercellular spaces with colloid substance as before men- 

 tioned, may have been what Baber observed. He states that 

 the reticulum (intercellular substance) stained with hematoxylin, 

 which makes it very different from the highly eosinophile net- 

 work observed by me. Baber's technique, however, seems to 

 have failed to produce the proper differentiation, since he actu- 

 ally succeeds in staining parts of the colloid with nuclear dyes. 



The disputed membrana propria was not observed. W. Miil- 

 ler, Kolliker and others claim to have seen it everywhere while 

 Schmid and others definitely deny its existence. The connective 

 tissue approaches the follicles and surrounds them but this loose 

 connective tissue sheath, which is by no means always present, 

 could scarcely be called a propria. 



The blood supply of the thyreoid gland is abundant and varies 

 somewhat with the species. Baber is the only observer who has 

 studied the conditions in the Teleost thyreoid by aid of the injec- 

 tion method, and unfortunately he used only one specimen of 

 the conger eel. 



The capillaries often approach the follicles so closely as to 

 seem imbedded between the epithelial cells. This is best shown 

 when both follicles and vessels are cut in cross section, (pi. IV, 

 fig. 6). Hiirthle describes a similar condition in the thyreoid 

 glands of young dogs and pictures them in plate II, fig. 6. The ' 

 epithelial cells often partly surround the capillaries by means 

 of processes, thus forming deep impressions. Baber speaks of 

 small intercellular projections from the capillaries which seem 

 to serve in retarding the circulation of the blood. 



There is usually a network of capillaries around each follicle, 

 four or five often being seen in cross section just outside the 

 epithelium, (pi. IV, fig. 5, a). In longitudinal section, the cap- 

 illaries at times surround almost the entire periphery of a fol- 

 licle. Such specimens illustrate how closely epithelium and 

 endothelium are neighbors without a separating basement mem- 

 brane, (pi. IV, fig. 5, E, Ca). 



