DEVELOPMENT OF PLANTS 



179 



would be largely concerned in reproduction and others in the 

 manufacture of foods, etc. This is essentially the state reached 

 by our higher plants which may be spoken of as a colony of cells. 

 Pandorina shows the earlier phases of the differentiation of the 

 gametes. This plant is really a spherical colony of about 16, prac- 



^D ME H 



FIG. 101. 



FIG. 102. 



FIG. 101. Features in the life history of Chlamydomonas: A, character 

 of the motile plant. B, conjugation of isogamous gametes. C, a plant 

 dividing to form numerous small male gametes. D, a plant forming two large 

 female gametes. E, male and female gametes about to conjugate. 



FIG. 102. Features in the life history of Pandorina: A, a colony of plants. 

 B, each plant of the colony dividing to form a new colony. C, the plants of 

 a colony escaping as gametes. D, the conjugation of two gametes of un- 

 equal size. E, later stage in the conjugation. F, gametospore or resting 

 spore. G, large zoospore formed from the gametospore. H, a colony formed 

 by the division of the zoospore, G. 



tically independent, motile plants, each one similar to Sphaerella 

 but held together in a mucilaginous mass (Fig. 102, A}. These 

 beautiful colonies multiply by each plant or cell dividing into 16 

 daughter cells which finally become an independent colony 

 (Fig. 102, B}. The gametes are formed in essentially the same 

 way as the colonies, save that the 16 daughter cells finally escape 

 as free swimming bodies (Fig. 102, C}, The mother plants or 

 cells producing these gametes differ in size, owing, doubtless, to 



