Fecundation of the Ovum. 395 



has also ascertained the cxisttncc of two modes of reproductioD, 

 oue by zoospores and the other by fecundation ; — at least the 

 presence of spermatozoids and female organs leads to a suppo- 

 sition of the latter. 



It is clear that fecundation must be a j)retty general phrcno- 

 menou in the Cryptogamia, and it is probably efi'ected throughout 

 by the entrance of the spermatozoids into the sporangia or arche- 

 gonia, A plant allied to Vauchcria, the Achlya prolifera, in 

 which linger, Alex. Braun, Thuret and De Bary have studied 

 the reproduction by zoospores, possesses spores of a second de- 

 scription, which are destituie of motion. These rather deserve 

 the name of sporangia, like those of Vavcheria. I'ringshehn 

 has ascertained the existence of a micropyle in them, and has 

 also pointed out the micropyle in the genera Bulhochcete 

 and (Edogoniuin. Besides the zoospores and the stationary 

 spores (sporangia), these two genera possess a third kind of 

 spores, first indicated by A. Braun under the name of micro- 

 gonidia^, and which, according to his observations, germinate, 

 and become converted into a small plant, usually composed of 

 two cells. It is remarkable that these microgonidia, the struc- 

 ture of which is exactly analogous to that of the zoospores, fix 

 themselves in (Edoffonium sometimes on the membrane of the 

 sporangia, and sometimes on the cell which is closest to them, 

 and in Bulbochate always upon the sporangia themselves. Prings- 

 heim draws attention to the fact, that these microgonidia, when 

 once fixed, open and pour their contents close to the micropyle 

 ill (Edogonium, and close to the cleft which takes its place in 

 Bulbochcetc. It is true that the existence of spermatozoids in 

 the microgonidia has not yet been detected ; but who can tell 

 what the future has in reserve for us ? It would be a great 

 advance in the knowledge of the Cryptogamia, if it should be 

 positively ascertained that the microgonidia arc a kind of an- 

 theridia, for A. Braun has proved the existence of them in a 

 great many families of freshwater Algas ; and it is probable, 

 from the observations of Thuret upon several families oi FucoidecB, 

 that they also occur in the marine Alga;. All that remains to 

 be proved is the existence of antheridia in the Palmellacece, the 

 Spirogyrce, the Desmidincecp, and the Oscillnriece, in order to give 

 us a complete and uniform picture of the development of the 

 Algae. 



The mother-spores of the Fuci and the sporangia of the 

 Vaucherice are, morphologically speaking, the homologues of the 

 central cell of the archegoniuni in the Ferns and Mosses, to 



* Beobachtungen iiber die Erschtinimscn dcr Verjiingunfr in dcr Natur. 

 Frcyhiirg. I'^l^-IK^O. fRay Society's Publications, 1^5:1) 



