90 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



together, they soon show manifestations of vegetation, and re- 

 produce the species. We have, therefore, spores vivified by 

 the impregnation of bodies, corresponding in their functions 

 with the spermatozoa of animals, and to some extent in their 

 genesis ; and the homologous bodies in the Ulothrix or Con- 

 ferva, are no more proofs that these genera belong to the 

 animal kingdom, than that Fuci should be excluded from 

 vegetables, because of the animal indications of their sperma- 

 tozoids. 



68. Owing to this exact resemblance between the spermato. 

 zoids of higher Algce, and the motile spores of many lower in the 

 scale, some doubt has been conceived as to their real functions : 

 but the direct experiments of Thuret have set such doubts at 

 rest. In some of the simpler Algse, however, the development 

 of the spermatozoids, and their effect in the vi^dfication of 

 spores, is more easily traced than in the Fucoidece ; and, 

 accordingly, we have a most valuable series of observations on 

 Vaucheria (Fig. 25), by Pringsheim, to whose kindness I am 

 indebted for the possession of his treatise.* The species prin- 

 cipally concerned in the investigation was Vaucheria sessilis, 

 an Alga consisting of a single branched and elongated cell, 

 without any dissepiments before the formation of the fruit. 

 Two little contiguous swellings appear on the side of the 

 thread, one of which rapidly elongates and becomes curved, 

 and the other meanwhile, assumes a more or less globose 

 form. A dissepiment is then formed in the middle of the 

 curved process, which is soon filled with minute oblong 

 spermatozoids, furnished on one side with two filaments, by 

 which they move. Meanwhile, a dissepiment has also formed 

 at the base of the globose body, whose endochrome alters its 

 appearance, a portion of the globule turned towards the male 

 organ, swelling into a little beak ; a part of the wall then gives 

 way ; the endochrome parts with some of its mucus, and a 

 passage is left open for the entrance of the spermatozoids ; the 

 endochrome after impregnation soon acquires a membrane, 

 and, ultimately, the whole is condensed into a spore, which 



* Moiiatsbei'iclite der KiJnigl. Ak. der Wissenschaft, Berlin, 1855. 



