146 University of California Publications. [zoology. 



4. — From the time the ovum leaves the germinal epithelium 

 there is a steady increase in its size until it reaches the boundary 

 of the budding region. If here it forms a union with a polypide 

 bud, the size increases somewhat until division occurs. If after 

 this union is effected, the polypide bud develops, the ovum grad- 

 ually grows smaller. Those, ova which fail of development, 

 decrease in size as they become more remote from the ovary. 



5. — Fertilization, if it occurs, takes place before or near the 

 time at which the union of hud and ovum is effected. In view 

 of the probable degeneration of the testis the possibility of 

 pailhenogenetic development is suggested. 



6. — During its development the embryo within an ovicell 

 becomes gradually inclosed by the bud which forms into a spher- 

 ical follicle consisting of several concentric layers of cells. 



7. — A characteristic feature of the early cleavage of Crista is 

 the complete separation of the blastomeres. This continues up 

 to the twenty or twenty-four cell stage when the blastomeres 

 unite into a more or less compact ball. 



8. — The separation of the blastomeres is accompanied by the 

 penetration between them of numbers of small cells, and by the 

 diminution of the concentric layers of the follicle. With the 

 continued growth of the embryo, the follicle being absorbed by 

 the embryo gradually disappears. 



9. — The primary embryo attains a size many times that of 

 the original ovum before it divides to form the secondary 

 embryos. In C. occidentalis, the secondary embryos divide to 

 form tertiary embryos which develop into ciliated larva 3 . At the 

 close of its proliferation the primary embryo itself becomes a 

 larva. 



I /.'.•,- ersiiy cf Cahfci .'.'■'•' 

 May, 1903. 



