OOPHYTA. 131 
chlorophyll-bearing, but a few are colorless saprophytes 
and parasites. 
272. Four classes have been distinguished: 
1. Zodsporee, analogous and related to the Zoésporee of Branch II. 
2. Gdogoniee ; plant-body a cellular filament. 
3. Celoblastee ; plant-body a tubular filament. 
4. Fucacee ; plant-body large and complex; color olive-green. 
Crass I. ZodsPorEs, 
273. The little spherical Volvox of the pools and ditches 
may be taken as an illustration of the first class. It resem- 
bles Pandorina in many respects, 
and without doubt is closely re- 
lated to.it. Volvox is a colony of 
very many little cells, each of 
which projects its two cilia out- 
ward, giving the ball a hairy ap- 
pearance. By the lashing of the 
cilia the ball rolls about in the 
water. Fie. £0. Volvox colony, 
. magnifies abou mes, 
274. At a certain stage some of showing young colonies with- 
the cells enlarge and slip into the 
interior of the colony, becoming free odgones, each con- 
‘taining one germ-cell. At the same time other cells break 
up their protoplasm into motile antherozoids, which escape 
into the same cavity of the colony. At length the anthero- 
zoids unite with the germ-cell, when asa result the latter 
secretes a thick wall, and thus becomes a resting spore. 
Upon germination the resting spore divides its protoplasm 
into several hundred small cells, which then arrange ‘them- 
selves into a new colony. 
275. The asexual reproduction takes place by certain 
cells breaking into great numbers of little cells, which then 
