VOLVOX. 



99 



At the anterior hyaline end, where the flagella are inserted, 

 there is a pigment spot ; the rest of the cell is green, owing 

 to the presence of chlorophyll corpuscles. In consequence 

 of the presence of these, Volvox is holophytic, i.e. it feeds 

 as a plant does and builds up starch granules. 



In its method of reproduction Volvox is of much biological interest 

 and importance. As Klein, one of its best describers, says, it is an 



v- 



FIG. 43. Volvox glob ator. After Klein and Janet. 



I. and V. Biflagellate individuals. II. Ripe ovum. III. A ball 

 of sperms. IV. A daughter colony developing . 



epitome ol the evolution of sex. Some of the colonies are asexual. 

 In these a limited number of cells possess the power of dividing up to 

 form little clusters of cells ; these clusters escape from the envelope of 

 the parent colony, and form new free-swimming colonies. In other 

 colonies there are special reproductive cells, which may be called ova 

 and spermatozoa. 



In V. globator the two kinds of reproductive cells are usually formed 

 in the same colony, the formation of spermatozoa generally preceding 

 that of the ova. Technically the colony may then be described as 'a 

 protandrous hermaphrodite. 



