PLATE 13 



EXPLANATION OF FIGURES 



Fig. 16 Photomicrograph of a transverse section taken through the caudal 

 end of the right subocular lymph sac (1) of an 18.25 mm. rainbow trout embryo 

 in which the subocular sac has become detached from the lateral pharyngeal 

 lymphatic (3). The lateral pharyngeal lymphatic is filled with blood. P. E. C. 

 944, slide 1, section 134. 



Fig. 17 Photomicrograph of a transverse section taken through the subocular 

 lymph sacs (/) of an 18.25 mm. rainbow trout embryo at the level of the optic 

 nerves, showing the position occupied by the superficial facial lymphatic (21) 

 which is filled with blood. P. E. C. 944, slide 1, section 78. 



REFERENCES 



1, Subocular lymph sac 6, Precardinal or jugular vein 



3, The lateral pharyngeal lymphatic 21, Superficial facial lymphatic 



100 



