(EDOGONIACE^: ; CHyETOPHO RACEME 



573 



same time an aperture is formed in the wall of the oogone by 

 which the antherozoid enters its cavity and fertilises its ob'sphere by 

 becoming absorbed into it. This mass then becomes an obspore (No. 3), 

 invested with a thick wall of its own, but still retains more or less 

 of the envelope derived from the cell within which it was developed. 

 The offices of these different classes of reproductive bodies are only 

 now beginning to be understood, arid the inquiry is one so fraught 

 with physiological interest, and, from the facility of growing these 

 plants in aquaria, can be so easily pursued, that it may be hoped 



FIG. 432. A, Sexual generation of CEdogonium ciliatum : 1, filament with two 

 oogones in process of formation, the lower one having two androspores attached to 

 its exterior, the contents of the upper oogone in the act of being fertilised by the 

 entrance of an antherozoid set free from the interior of its androspore ; 2, free 

 antherozoids ; 3, mature oospore, still invested with the cell-membrane of the 

 parent-filament ; 4, portions of a filament bearing special cells, from one of which 

 an androspore is being set free ; 5, liberated androspore. 



B, Branches of Chcetophora elegans, in the act of discharging ciliated zob'spores, 

 which are seen as in motion on the right. 



that the zeal of microscopists will not long leave any part of it in 

 obscurity. 



The Chaetophoraceae constitute a beautiful and interesting little 

 group of confervoid plants, of which some species inhabit the sea, 

 whilst others are found in fresh and pure water rather in that of 

 gently moving streams, however, than in strongly flowing currents. 

 Generally speaking, their filaments put forth lateral branches, and 

 extend themselves into arborescent fronds ; one of the distinc- 

 tive characters of the group is afforded by the fact that the 

 extremities of these branches are usually prolonged into bristle- 



