PLATE 6 



EXPLANATION OF FIGURES 



48 Preparation of the periphery of the posterior lobe of an Acanthias embryo 

 approximately 20 mm. long showing the terminal buds of the hepatic network 

 and the attachment of the network to the mesothelial covering by means of mesen- 

 chymal strands. 



44 Thick frontal section of the liver of an embryo of Mustelus canis approxi- 

 mately 12 mm. long. The large hepatic duct and the hepatic tubules lie in a 

 vascular sinus which is represented in black. The vertical band seen on the right 

 hand side is a section of the mesothelial covering of the liver. 



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