200 JEREMIAH S. FERGUSON 



the major portion is clearly homogeneous. The well-known fila- 

 ments pass at frequent intervals from the colloid mass to the 

 epithelial surface. Some of these filaments can be traced to the 

 free surface of the epithelial cell while others quite clearly enter 

 the intercellular spaces, where, in tangential sections of the fol- 

 licle, they form intercellular masses simulating the net-work de- 

 scribed by Baber ('81) and interpreted by Langendorf ('89) as 

 the ramification of colloid cells. 



Occasionally the colloid mass appears to have been disinte- 

 grated into small spherules .007 to .008 mm. in diameter (fig. 15). 

 The size of these spheres is suggestive of the red blood cells of 

 mammals, but the red cells of Elasmobranchs are ovoid and larger. 

 Of the spherules some are distinctly acidophile but many are 

 slightly basophile, none, or very few, are strongly basophile. All 

 the spherules are homogeneous, and I have observed in the more 

 basophile no tendency to chromatolysis such as one might expect 

 to find if the spherules of this type were thought to represent de- 

 generating nuclei of the red cells, nor have I been able to trace 

 stages of transition from the nucleus to the basophile spherule. 

 Since all the blood cells of the species studied are nucleated one 

 could not well infer that the acidophile spherules could represent 

 any stage in the disintegration of red blood cells, for none of these 

 spherules contain even traces of chromatin. On the other hand, 

 both red and white blood cells can occasionally be found within the 

 colloid quite independently of the spherules I have described; 

 in this particular the Elasmobranch thyroid is in accord with the 

 well known structure in other vertebrate orders. The appear- 

 ance, location, disposition and reactions of the spherules indicate 

 their origin from the solid colloid masses, from which they would 

 appear to be formed by disintegration with progressively increas- 

 ing basic reaction. That the reverse process occurs, viz., that the 

 spherules may represent intermediate stages in the formation of the 

 colloid masses, is contraindicated by the fact that only very few 

 follicles contain spherules, nor does there appear to be any indica- 

 tion of a tendency of the spherule to fuse. On the other hand, a 

 tendency to further disintegration is quite apparent, and the 

 possibility is suggested that the colloid in this way may be trans- 



