PLATE 16 



EXFLANATIOX OF FIGURE 



Fig. 21 Photomicrograph of a transverse section taken through the subocular 

 lymph sac {1) in a seventeen-day steelhead trout embryo in which the sac presents 

 a multilocular appearance; high magnification. P. E. C. 522, slide 1, section 95; 

 injected embryo. 



REFERENCES 



1, Subocular lymph sac 22, Carotid artery 



106 



