OTIC VE,SICLE 



SPINAL CORD 



NOTOCHORD 



SEPTUM 



TRfiNSVERSUM- 



LIVER COMPLEX 



LEFT DIVISION 

 BULBUS CORDIS 



fl^% ; ?T'"f ^''''y ^'""^ ^^"^P"'^' '^^^'"8 development of early systems. 

 (A) Frog tadpole (R. pipiens) of about 6^7 mm. It is difficult to determine the exact 

 number of vitelhne arteries at this stage of development and the number given in the 

 figure is a diagrammatic representation. (A') Shows right and left ventral aortal divi- 

 figu"res 28o"ind%T5'"'^''' ^^^ '^"^^""^y of frog tadpole of about 10-18 mm. See also 



537 



