PLATE 22 



EXPLAXATIOX OF FIGURE 



Fig. 29 Photomicrograph of a transverse section of a twenty-day rainbow 

 trout embryo, taken through independent anlagen {3') of the lateral pharyngeal 

 lymphatic, at about the level of the first efferent aortic arches; compare 3' in fig- 

 ures 8 and 29. P. E. C. 668, slide 1, section 122; injected embryo. 



REFERENCES 



3', Independent anlagen of the lateral 15, Hyoidean artery 



pharyngeal lymphatic which lie an- 16, First efferent aortic arch 



terior to the otic communication 27, Root of dorsal aorta 



6, Precardinal or jugular vein 



118 



