t>»* Fecundation of the Ovum. M ^395 



has also ascertained the existence of two modes of reproduction, 

 one 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 pretty general phseno- 

 menon in the Cryptogamia^ and it is probably effected throughout 

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

 gonia. A plant allied to Vaucheria, the Achlya prolifera, in 

 which Unger, Alex. Braun^ Thuret and De Bary have studied 

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

 scription, which are destitute of motion. These rather deserve 

 the name of sporangia, like those of Vaucheria. Pringsheim 

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

 also pointed out the micropyle in the genera Bulbochcete 

 and (Edogonium. 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 inicro- 

 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 (Edogonium sometimes on the membrane of the 

 sporangia, and sometimes on the cell w^hich is closest to them, 

 and in BulbochcBte 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 

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

 Bulbochcete. 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 are a kind of an- 

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

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

 from the observations of Thuret upon several families oiFucoidecBj 

 that they also occur in the marine Algse. All that remains to 

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

 Spirogifrce, the Desmidiacece, and the Oscillariece, in order to give 

 us a complete and uniform picture of the development of the 

 Algse. 



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

 Vaucherice are, morphologically speaking, the homologues of the 

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



* Beobachtimgen liber die Eischeinungen der Verjiingung in der Natur. 

 Freyburg, 1849-1850. (Ray Society's PuWicatiQns/l853.) 



