484 



LIFE-HISTORIES 



The smaller motile protoplast is plainly the male gamete, and 

 the larger, non-motile one, the female. Hence the cells in which 

 they arise may be called respectively the male and the female 

 gametangia,^ the cells in which non-sexual spores appear, being 

 termed sporangia:- Union of a male with a female gamete is dis- 

 tinguished as fertilization. As a result of this process in Coleocha?te 

 the fertilized gamete, still remaining within the gametangium, en- 

 larges, and incloses itself in a new cell-wall, thus forming what is 

 called an oospore,^ which becomes further protected by an envelope 

 of branches (r, Fig. 315 B); for a cell at its base is stimulated to 



Fig. 315. — Cushion Sheath-alga {Coleochcete pulvinata, Sheath-alga Family, 

 Coleochcetacete). A, part of a thallus bearing male {an) and female 

 {og, og") gametaugia; and bristle-like projections sheathed at the 

 base {h, h); male gametes, z, z, 202. J5, ripe oospore in its rind (r). 



C, oospore germinating by the formation of swarm -spores {sch). 



D, swarm-spores of different ages. B-D, «t°- (Pringshcim.)^ 

 Found with the other species, forming small cushions. 



produce several new cells, which, growing up around the game- 

 tangium-base and oospore produce a sort of rind. Thus protected 

 the oospore rests through the winter. In spring the protoplast, by 

 division of its nucleus and the formation of partitions, is transformed 

 into a little mass of cells firmly united with one another but quite 

 distinct from the old cells surrounding them. In this little mass 

 we have, in fact, a new plant entirely different from the sexual 

 plant which produced it. It never produces gametes, but from each 

 cell comes a single swarm-spore which under favorable conditions 



' Gam"e-tan'gi-um < Gr. angeion, a vessel. 



^ Spor-an'gi-um < Gr. spora, spore. 



* O'o-spore < Gr. oon, an egg. 



