194 



E. H. NORMS 



tributed throughout the gland mass. Whether these are intra- 

 or intercellular spaces cannot be said, for the cell boundaries are 

 not visible. The margins of these spaces are extremely irregular 

 and indistinct, blending almost imperceptibly with the faintly 

 staining cytoplasm. These changes are shown in figure 3. 



In embryos of 5.8 mm. the structure of the gland is again 

 changed. As pointed out in the preceding section, the thyreoid of 



5fclG.Pl. 



Fig. 3 Drawing of a part of a cross-section of an Acanthias embryo 5 mm. 

 long (No. 6). Ec, ectoderm; G.P.I, first gill pouch; H.C., head cavity; L., lumen 

 of pharynx; T., thyreoid; V., vacuole-like spaces. X 300. 



