REPRODUCTION. 



67 



eralized as consisting of division and segregation, followed by 

 aggregation. 



The subdivision (segmentation) of the cell, after the quies- 

 cence referred to, again commences, but in a plane at right 

 angles to the first, from which four sgheres result, again to be 

 followed by the resting stage. The process continues in the 

 same way, so that there is a progressive increase in the number 



Fig. 65.— The cleavage of a frog's egg (10 times enlarged). A, the parent-cell; B, the 

 first two cleavage-cells; C, 4 cells; D, 8 cells (4 animal and 4 vegetative); M, 12 

 cells (8 animal and 4 vegetative); .F, 16 cells (8 animal and 8 vegetative); G, 24 

 cells (16 animal and 8 vegetative); H, 32 cells; 7, 48 cells; K, 64 cflls; i, 96 cleav- 

 age-cells; M, 160 cleavage-cells (128 animal and 32 vegetative). (Haeckel.) - 



of segments, at least tip to the point when a large number has 

 been formed. This is rather to be considered as a type of one 



