348 Dr. Pringsheim on the Germination of Alga, 



tion of the spermatozoids into the mass, and the subseqtient for- 

 mation of the cellulose coat of the spore. 



[These observations render necessary a careful re-examination 

 of the impregnation in the higher plants. It is by no means 

 certain that the so-called germinal vesicles in the embryo-sac of 

 the flowering plants possess a cellulose coat before the influence 

 of the pollen-tubes has been exerted. This point was not ascer- 

 tained in my observations on Orchis morio ; and I have observed 

 appearances since, in Santalum album and other plants, which 

 render it probable that the germinal bodies are only globular 

 masses of protoplasm at the moment of impregnation. — A. H.] 



Florideje. 



The interpretation of the reproductive structures of this class 

 is still very imperfect. From some observations made lately on 

 CeramidBj Dr. Pringsheim is induced to regard the tetraspores as 

 gemmse, or gonidia. But the capsule-spores germinate in a totally 

 diff*erent way, — not growing at once into plants like the parent, 

 but producing an irregular structure, which the author suggests 

 may be a kind of prothallium, analogous to that of the Ferns. 

 However, his experiments on the cultivation of these bodies 

 were unsuccessful. 



Sphacelaria. — Cladostephus. 



Thuret discovered the existence of antheridia in Cutleriaj con- 

 taining spermatozoids, very difierent from the antheridia of Fucus, 

 Pringsheim has detected antheridia in Sphacelaria tubuloides, 

 more resembling those of Fucus, These antheridia consist of 

 one or more large cells formed in the sphacelce at the ends of 

 the branches. Their contents become converted into a quantity 

 of minute roundish bodies, at first much resembling the mass of 

 spermatozoids in the unopened antheridia of the Mosses. The 

 antheridial cell at length grows out laterally into a tube, which 

 breaks through the wall of the sphacela, and opens at the point 

 to discharge the mass of spermatozoids. These are very minute 

 clear vesicles, without a brown spot, and in so far resembling 

 those of the Floridese ; but they possess two cilia, like those of 

 the Fucacese, and move actively in the same manner. The 

 author had no female plants at command, and consequently 

 could not observe the further history of the reproduction. 

 Somewhat similar antheridia, opening by a tubular process, 

 were observed last summer in Cladostephus spongiosm. 



Freshwater Alg^e. 

 The author next proceeds to consider the general question of 



