IN TUB VEGETABLE KINGDOM. 33 



escape by perforations in the walls ; the autherozoids again 

 originate in special cells of the nature of antheridla. Tlu'v 

 are both indeed concerned in propagation, bnt while tin- 

 peculiar office of the latter is to impregnate the germs, the 

 zoospores appear to be merely a kind of gemmae capable of 

 spontaneous development, for it is observed that after a 

 time their motion ceases from the loss of the ciha, and they 

 begin to o-enninate into new fronds. 



Only such particulars of the reproductive process in the 

 minor divisions of the order will be noticed here as are 

 illustrative of the main points now under consideration. 

 To beoin with the Confervoideaj — as limited to the ffreen- 

 coloured Algte, both fresh water and marine, which do not 

 conjugate — w^e may take for illustration of the filamentous 

 species, formed by the coherence of cells in linear series, 

 those contained in the genera Sphceroplea, Bulbochwte and 

 CEdogonium, as having been the subjects of the most satisfac- 

 tory observations. Zoospores have been detected only in some 

 of the species, but the occurrence of autherozoids appears to 

 be general. They are developed from special cells, either 

 directly as in Bplia^roplea, or through the medium of a pro- 

 thallial frond or androspore, as in various species of the 

 other two genera. In the latter, according to the observa- 

 tions of Pringsheim, small bodies like zoospores (micro- 

 ponidia) are formed singly in cells, which are smaller than 

 the rest, and present certain other peculiarities. These 

 corpuscules, after their period of activity is over, attach 

 themselves to the neighbourhood of the sporangia, and ger- 

 minate into minute fronds of three cells, one of which serves 

 as a pedicle of attachment, while the other two become 

 antheridia, each maturing an antherozoid of some size. By 

 a peculiar fissuring of the anthericUum, and the formation 

 of a pore or micropyle in the sporangium, the antherozoi<l 

 passes from its own cell to that containing the globular 

 mass of o^erminal matter, in the substance of which it seems 



c 3 



