106 



BOTANY 



There are usually two spermatozoids produced in each antheridial cell. These 

 closely resemble the swarm-spores, but are much smaller, with little or no 

 chlorophyll, and are largely made up of the nucleus of the mother-cell. 



FIG. 76. A, cell of Pithophora cedogonia (X 75). 



spore. 



B, aplanospore. C, germinating 



Fertilization. The spermatozoid enters the egg at the receptive spot, and 

 quickly penetrates its substance, where it fuses with the egg-nucleus. The egg- 

 cell now secretes a firm membrane, which generally becomes dark colored, and 

 the contents lose the chlorophyll and sometimes become bright red. Germina- 

 tion takes place after 



A B a period of rest, by 



the division of the con- 

 tents of the spore, in- 

 to four swarm-spores, 

 each of which gives 

 rise to a new plant. 



Coleochaete. The 

 highest of the Confer- 

 voidese belong to the 

 genus Coleochsete 



(Figs. 77, 78), of 

 which there are several 

 species growing in 

 fresh water, usually 

 attached to the leaves 

 and stems of various 

 aquatics, such as 

 Water-lilies, Rushes, 

 etc. The commoner 

 species (Fig. 77) are 

 flat disks, the cells 

 each containing a sin- 

 gle chromatophore and 

 nucleus. Growing from 

 many of the cells are 

 curious hairs, with a 

 sheathing base, from 

 which the plant gets 

 its name. Swarm- 



D 



an 



FIG. 77. A, Coleochsete scutata (X75). B, single cell 

 with hair (X 200). C, vegetative cells and antheridia 

 (X 200) . D, young oospores, og, imbedded in the thallus. 



