24 British Fitngi. 



Zygospores are produced by tlie primitive algal-like 

 fungij and are homologous with the zygospores in the 

 simple green algse. In the second method of sexual 

 spore production the sexual organs are distinctly 

 different in size and function. The male organ or 

 antheridiiim is usually much smaller than the female 

 organ or oor/onium. In many instances the oogonium 

 is the enlarged terminal cell of a hypha, which increases 

 in size until it becomes spherical^ the antheridium 

 growing out as a lateral club-shaped branch from the 

 hypha immediately below the oogonium. When the 

 oogonium and antheridium are replete with proto- 

 plasm_, the cavity of each is cut off from communication 

 with the cavity of the hypha by the formation of a 

 transverse septum. 'Next a portion of the protoplasm 

 in the oogonium forms a spherical mass, which is 

 known as the oosj^here. After this differentiation has 

 taken place, the antheridium comes in contact with the 

 wall of the oogonium, and at the point of contact 

 develops a slender outgrowth called the fertilization- 

 fuhe, which pierces the wall of the oogonium, and 

 increases in length until it comes in contact with the 

 oosphere. Through this fertilization-tube the proto- 

 plasm and nucleus contained in the antheridium passes 

 and mingles with the protoplasm of the oosphere. 

 After this blending of protoplasm, which constitutes 

 fertilization, the oosphere is called an oosijore, which 

 undergoes further changes, clothes itself with a firm 

 cell-wall, and usually after a period of rest, germi- 

 nates and gives origin to a new individual. Sometimes, 

 as already stated in the case of Peronos2:)ora, the 

 oogonium is formed from an intercalary cell of a hypha 



