PLATE 12 



EXPLANATION OF FIGURES 



Fig. 14 Photomicrograph of a sagittal section taken through the head and 

 pharynx of a twenty-two-day rainbow trout embryo; showing the relations of 

 the subocular lymph sac (1) to the eye, the hyoidean artery (15) and the olfactory 

 pit (53); injected embryo. P. E. C. 816. 



Fig. 15 Photomicrograph of a transverse section taken through the subocular 

 lymph sacs of a twenty-day steelhead trout embryo. The subocular sac (1) on 

 the right side of the figure is filled with blood, which has passed into the sac from 

 the veins through the lateral pharyngeal lymphatic. P. E. C. 636, slide 1, sec- 

 tion 67. 



REFERENCES 



1, Subocular lymph sac 15, Hyoidean artery 



6, Precardinal or jugular vein 33, Olfactory pit 



98 



