THE VITAL PROPERTIES OF THE CELL 



289 



When two swarm-spores meet, they first touch each other with 

 their points (IV), and then fuse together to form a biscuit-shaped 

 body, which gradually draws itself up into a ball (VI, VII, X). 

 This surrounds itself, a few minutes after fertilisation, with a 

 cellulose cell-wall, and then, as a zygote, enters into a resting 

 condition, during which its original green colour becomes brick- 

 red. 



A sexual difference is seen in Eudorina elegans, a species which 

 is very similar in other respects to Pandorina, being also a 

 gelatinous sphere containing from sixteen to thirty-two cells 

 (Fig. 158). At the time of fertilisation the colonies become 

 differentiated into male and female. 



Fio. 158. Eudorina elegans, female colony (Ccenribium), around which antherozoids, Sp, 

 are swarming (after Goebel ; from Sachs, Fig. 412) : M l M 3 bundle of antherozoids. 



In the female colonies the individual cells transform themselves 

 without further division into globular eggs; in the male colonies, 

 on the contrary, each cell splits up by means of repeated divisions 



u 



