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MALL. 



[Vol. VIII. 



shown us how the spongioblasts are formed and his view is in 

 general confirmed by the present study. It is quite easy to 

 follow their formation in Amblystoma, because the cells of the 

 retina are loaded with yolk and pigment granules. Just before 

 the stage pictured in Fig. 4 is reached, the nucleus is in the 

 free end of the cell and as it moves towards the base of the 

 cell the protoplasm of its peripheral end is gradually broken up 

 into a mass of fibrils. By what process this takes place is 

 extremely difficult to determine, but as the fat globules vanish 

 from the peripheral end the pigment adheres to the protoplasmic 



Fig. 5. — Section through the eye of Amblystoma (6.5 mm. long) thirteen days 

 before hatching. X 133 times. C, germinating cell ; S, spongioblast. 



filaments of these cells and soon we have spongioblasts as indi- 

 cated in Fig. 5. The cell process arising from the spongioblasts 

 often appear to communicate with one another but careful 

 study of many specimens indicates that in all probability this 

 is not the case. Any line of pigment granules communicates 

 only with the body of one cell and does not continue over 

 to that from a neighboring cell. This view is materially 

 strengthened by the observations of Ramon y CajaP upon the 



1 Ramon y Cajal, Anatom. Anz., 1889. 



