REPRODUCTIVE ORGANS OF ALGZ.—(CDOGONIUM. 399 
of the antheridia, becomes attached to the oogonium, forming 
what is known as a dwarf male plant (jig. 869, a, m, m), and 
subsequently discharges its protoplasm in the form of an anther- 
ozoid, by which the oosphere may be fertilised, and become 
transformed into an cospore. 
In either case the oospore after a short period of rest gives 
rise to four swarm-spores (fig. 869, D), each of which (fig. 869, 
E) subsequently grows into a swarm-spore-producing plant, so 
that in Gidogonium we have another ‘example of alternation of 
generations, similar to that which occurs in Vaucheria (page 
394), viz., one in which a series of generations consists of the 
swarm-spore-producing plant, whilst at more or less regular in- 
tervals a sexual generation takes place. It should be noted 
however that zoospores may be also produced in the same indi- 
vidual plant as that in which the sexual process takes place. 
