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, z.e. it feeds 
as a plant does and builds up starch granules. 
In its method of reproduction Vo/vox is of much biological interest 
and importance. As Klein, one of its best describers, says, it is am 
Fic. 43.—Volvox globator.—After Cohn. 
a, Balls of sperms ; 4, immature ova ; c, ripe ova. 
epitome of 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. 
