Mr. Hassall's Notices of British Freshwater Conferva. 341 



proceed remain often many months without any change in 

 them, while they dissolve immediately in the true Con- 

 ferva." 



I can affirm, without fear of error, that the statement con- 

 tained in the last paragraph, so far as any species of Fresh- 

 water Conferva? with simple filaments is concerned, is wholly 

 destitute of foundation. The elliptical bodies, which I regard 

 as the true spores, remain in all the species of the group Ve- 

 siculaspermae as long in a quiescent state as they do in the 

 Conjugate ; and what good reason, may I ask, could be assign- 

 ed why they should not, seeing that they are organized alike 

 in both ? 



M. Agardh suggests the questions, what may be the pur- 

 pose served in the oeconomy of the plant by this motion of 

 zoospores? and how is it carried on? Preparatory to re- 

 quiring the solution of these questions, I should wish to know 

 the exact manner in which the investing membranes of the 

 spores are disposed of, prior to the escape of the numerous 

 zoospores which each of the elliptical or spheroidal bodies are 

 said by the younger Agardh to furnish, by their disintegra- 

 tion. 



In a recent memoir on the classification of the Algae, pub- 

 lished in the e Annales des Sciences Naturelles y for May 1842, 

 M. J. Decaisne, who differs in many points from Agardh, re- 

 lates an additional fact, which stands opposed to Agardh's 

 observations, on the separation of the elliptical or spheroidal 

 bodies of the Conjugate into n umerous zoospores. " On press- 

 ing out/ 5 says M. Decaisne, " the contents of one of these 

 when in a mature condition, and examining them, no trace of 

 any bodies can be detected from which it might be supposed 

 that the zoospores proceeded, the entire contents consisting 

 of globules of an oleaginous appearance, and of air, of different 

 volumes, mixed up with a jelly-like turbid fluid." Upon the 

 subject of the motion of the zoospores, M. Decaisne thus ex- 

 presses himself: — 



" I must declare that I have never been so happy as to wit- 

 ness in the freshwater Confervas either the escape of the cor- 

 puscles by the displacement of their fibres, or the production, 

 on the surface of the same plants, of a papilla perforated by 

 means of the reiterated shock of the reproductive bodies. 

 The membrane of the Confervas, like that of the Algae in gene- 

 ral, has always appeared to me smooth, and destitute, even 

 to a very high power, of all filamentous organization before its 

 disorganization. 



"My opinion, therefore, differs from that of Agardh on the 

 subject of the zoospores properly so called. These corpuscles, 



