290 Transactions. — Botany. 



and to guide themselves, the former to their relative gymnospores, the latter 

 to appropriate places whereon to rest and recommence the process of ger- 

 mination and growth. 



In the methods of fructification, moreover, the resemblances between 

 flowering plants and Alg^ are probably as close as in any other particular. 

 Setting aside the Yolvocinea, Palmellace(B, and some others in which the 

 process of multiplication is merely a process of cell division, either intrin- 

 sic or extrinsic, we find in the ConfervcB, SiphonacecB, Oscillatorie(E, etc., 

 that the single cell has the power of producing reproductive spores, thus 

 (keeping in mind that an algal cell is the equivalent of a phsenogamic 

 flower) affording an analogy with the class of so-called hermaphrodite 

 flowers. A strictly monoecious form of fertilization is met with in the 

 (Edogoniacem, where the contents of certain inflated cells are vivified by the 

 contents of contiguous antheridial cells which, by rupture of the cell divi- 

 sion, gain access to the inflated cells. A distinct advance upon this method 

 is found in many (Edogonia and ChcctophorcB. Here the distinction between 

 antheridial and sporidial cells is evident — they often occur upon different 

 filaments, though sometimes upon distant portions of the same, and are 

 easily recognized by their shape and appearance. The contents of the 

 antheridial cell (androspore) when mature escape through rupture of the 

 cell wall, and, being furnished with cilia, lead an active locomotor life until, 

 coming in contact with the gonidial cell (oospore), the locomotion comes to 

 an end and the contents of the two combined form a zoospore which 

 eventually becomes a young plant. 



The ZygnemacecB are veritable dioecious plants, and propagate by a 

 process of conjugation — the cells of two contiguous filaments throw out a 

 connecting tube through which the contents of one (the antheridial) cell 

 pass into the other (the gonidial), and thus fertilize them, the result being 

 a zoospore. In this process the fertilization of the ovule by the pollen tube 

 in Phanerogams is closely imitated. But further, that abnormal self-fertili- 

 zation that takes place in certain flowers under unusual conditions, and 

 which is termed cleistogamy, would appear to occur at times in certain 

 SpirogyrcB, the filaments of which have the power of producing zoospores — 

 the so-called pseudogonia — in certain cells without conjugation ; in fact 

 these cells are, like the cleistogamous flowers, not only hermaphrodite, but 

 contain within themselves the power of self-fecundation. 



In the following Hst of fresh-water AlgaB which have come under my 

 observation during the last eighteen months I have included only such as I 

 feel pretty certain I have verified. Many others are not enumerated, because 

 I am at present doubtful of their classification ; but with further search and 

 observation I have no doubt the hst may be extended indefinitely. 



