Oll tlie laiviil dovelopment of Amia calva. 661 



as in Serranus. Aiul it is further evident that the more intimate 

 the relatiou of the yolk to the liver becanie, tlie less intimate would 

 be its connection with the gut, — i. e., the earlier it would become 

 separated from the wall of the digestive tube, — as the conditiuus in 

 Serranus denionstrate. 



A final Word contrasting the mode of developnient of the liver 

 in Ämia and in Teleosts. In this regard the prccociousness of Ser- 

 ranus is again to be uoted. l'he liver here arises, not as a caecum, 

 but as a solid outgrowth, which branches almost at once and later 

 acquires a lumen through the dissociation of its cells. 



That the periblast nuclei are directly concerned in the formation 

 of blood cells the present writer has been unable to decide. In the 

 Teleosts this disputed view certainly receives no confirmation, but in 

 Ämia, where the yolk material has still its primitive relations to the 

 intestinal veins, the conditions appear to be worthy of more careful 

 study. Although the writer has not attempted to follow the histo- 

 genesis of the blood cells, he has noted that cells occur in the peripheral 

 periblast, that these especially on the side away from the gut, 

 become greatly enlarged and then undergo division, and that their 

 products, lying in the outermost periphery of the periblast zone, cer- 

 tainly resemble very closely the blood cells which fill the capillaries 

 immediately adjoining. 



d) Pronephros. 

 Little can here be added to the studies of Jungersen on the 

 pro- and mesonephros of larval Ämia. The results of this author 

 have been confirmed as far as the present observations have been 

 carried. It has thus been found that 1) there are but two functional 

 pronephric funnels at the time of hatching; 2) the segmental arrange- 

 ment of the mesonephric tubules corresponds to that of the muscle 

 plates; 3) the mesonephric tubules are not evaginations of the Peri- 

 toneum, but are formed independently of it, in the neighborhood of 

 the pronephric duct, into which they later establish their opeuings; 

 4) close relations exist between the larval excretory System of Ämia 

 and the Teleosts. The foilowing is the only addition to the results 

 of Jungersen which can now be given. In the stage 24 hours before 

 hatching the pronephric duct is relatively wider than that shown by 

 Jungersen in his first figure, and is lacking in snake-like twistings. 

 The hinder portion of the duct is straight, its anterior division crook- 

 shaped, bending inward and slightly downward. Its extreme tip opens 



