348 



BOTANY. 



consists of a rounded oosphere situated within a cayity-^the 

 oogonium ; it is developed from one of the cells (sometimes 



two) of the filament 

 by a condensing 

 and rounding off 

 of the protoplas- 

 mic contents; when 

 the oosphere is ful- 

 ly formed, an open- 

 ing is formed in 

 the oogonium-wall 

 for the ingress of 

 the spermatozoids 

 {A and B, Kg. 

 le?). One or more 

 spermatozoids are 

 produced in each of 

 certain small cells 

 which are formed 

 from the large ones 

 by a process of 

 simple fission ; in 

 shape they resem- 

 ble the zoospores 

 mentioned above — 

 that is, they are 

 oval and provided 

 with a crown of 

 vibratile cilia on 

 their smaller ex- 

 tremity (Z), z, z, 

 Fig. 167). Upon 

 escaping into the 

 water, which is ren- 

 dered possible by 

 a splitting of the 

 wall of the motlier- 



Pig. 167 —A, middle part of a sexual filament of <Sdo- 

 ffonium ciliatum (Androgynia of Wood), with male cellB 

 aheve at m; og, oogonia (fertilized) ; m, dwiirf male 

 plants attached to the side of the oogonia, the eperma- 

 tozoids already discharged. X 350. S, oo<;onium, Off^ 

 at the moment of fertilization ; o. the oosphere ; e, the 

 Bpermiitozoid forcing its way into the oosphere; »i, the 

 dwarf male plant.' C, ripe oospore. D, (Edogonvmn 

 gemfUiparwm (Pringtheimia of Wood), part of the male 

 filament, with spermatozoids, s, issuing from the cells. 

 E, part of a branch of Bufbochwte intermedia, vnXh oogo- 

 nia, the uppermost containing an oospore, the middle 

 one wii h an oospore escaping, the lower empty. F, four 

 zoospores resulting from an oospore of Bumichaete. Q, 

 eoospore come to rest and germinating.— After Prings- 

 heim. 



cell, they swim about vigorously, and eventually make their 

 way through the opening in the oogonium, and then burj 



