70 



MANUAL OP BOTANY 



^-^y^^- 



sexual apparatus is formed, but it is doubtful how far actual 

 fusion of the gametes takes place. 



The gametes may be alike. In this case they are never set 

 free from the gametangia, but the walls of the latter coalesce and 

 fusion takes place inside the structure so formed, a zygospore 

 being the result {fig. 820). These isogamous fungi form the 

 group of the Zygomycetes. 



In other cases both male and 

 female gametes are found. The 

 female is usually an oosphere, 

 contained either singly or in 

 numbers inside a structure that 

 may be called an oogonium {fig. 

 821). In this case the male 

 usually consists of a mass of 

 naked protoplasm, which occurs 

 in a special branch of one of 

 the hyphse, in close proximity 

 to the oogonium. This branch 

 is' known as a polUnodium {fig. 

 821, aw). In another section the 

 male gametes are differentiated 

 and are set free. They are small 

 rounded cells, clothed with a cell- 

 wall, and known as spermatia. 

 They are produced by abstriction 

 from the apex of a special filament, 

 the sterigma, a number of these 

 being developed in a, special re- 

 ceptacle, the spermogoniuvi. The 



into contact at their apices, and each female organ, which is known as 



has cut off from itself a cell. s:yg. „„ rt«„7,v«««,*, / j;™ r7oo\ „i. ■ 



Zygospore resulting from the fusion ™ arcUcarp {fig. 783), contams 



of these cells, zyg'. Adult zygospore no differentiated female cell, and 



after germination, p. Promycelium n i. x, . ^ 



bearing a sporangium, sp. corresponds to the procarpmm of 



the Rhodophyoese. This some- 

 times has a trichogyne, as in the latter group. 



In some forms which bear an archicarp the male cell is not 

 dififerentiated either, but is much like the gamete of the group 

 last mentioned, being produced by a hypha close to the 

 archicarp. The product of fertilisation in the last two cases is 

 known as an ascocarp, and is the sporophyte of the plant. 



The spores or gonidia of fungi are borne in great numbers, and 

 receive different names according to the organs in or on which 



Fig,S2Q. Conjugationin Mucor Mucedo. 

 Two hyphse which have come 



