PLATE 23 



EXPLANATION OF FIGURES 



Fig. 30 Photomicrograph of a transverse section of a twenty-two-day rainbow 

 trout embryo, taken at about the level of the first efferent aortic arches; showing 

 that the continuous lateral pharyngeal lymphatic (3 in figures 10 and 30) occupies 

 the same relative position in the walls of the pharynx as its independent anlagen 

 {3' in figures 27, 28 and 29) of earlier stages. The medial pharyngeal lymphatic 

 (4) and independent anlagen of the precardinal lymphatics (5') are also shown in 

 figure 30. P. E. C. 648, slide 2, section 17. 



Fig. 31 Photomicrograph of a transverse section of a seventeen-day steel- 

 head trout embryo, taken through independent anlagen {3') of the lateral pharny- 

 gea lymphatic at about the level of the hyoidean arteries; compare 3' in figures 

 6 and 31. P. E. C. 740, slide 1, section 88; injected embryo. 



REFERENCES 



3, The lateral pharyngeal lymphatic; 

 a continuous vessel through which 

 the subocular lymph sac drains into 

 the veins in the trout 



3', Independent anlagen of the lateral 

 pharj'ngeal lymphatic which lie an- 

 terior to the otic communication 



4, Medial pharyngeal lymphatic 



5', Independent anlage of the pre- 

 cardinal lymphatic which lies con- 

 tiguous to the precardinal vein and 

 just caudal to the medial pharyn- 

 geal communication (see fig. 10) 

 6, Precardinal or jugular vein 

 15, Hyoidean artery 

 27, Root of dorsal aorta 



120 



