260 SUMMARY OF CURRENT RESEARCHES RELATING TO 



septa at the time of reproduction when the short branchlets are 

 isolated for that purpose. At all events, successive septation of the 

 main filament does not appear to have been recognized by any one 

 who has written upon this family. Of its development it is stated 

 that the lower part of the germ-cell grows out into a branched, 

 pale-coloured root, and the upper part is elongated in a still more 

 considerable degree into a stem-like filament, which grows on and on 

 by apical development imtil its growth is finally arrested by fructifi- 

 cation. That is, in efiect, the recognition of Vaucheria as uni- 

 cellular. 



During the keen weather at the commencement of the present 

 winter, Mr. F. Bates collected some filaments of Vaucheria from 

 under the ice, and upon submitting them to the Microscope discovered 

 that the main threads were much divided by septa. Dr. Cooke 

 received portions of these threads mounted, and as there was no 

 positive evidence of the. filaments belonging to Vauclieria, he was 

 prompted to affirm that some filaments of Cladophora must have been 

 mixed with the Vaucheria, for not only were the threads distinctly 

 septate, but there was an accumulation of plasma in the cells, and an 

 appearance as of difiierentiation. Subsequently, however, all doubts 

 were removed, for in a part of the gathering were seen the oogonia 

 and antheridia so characteristic of Vaucheria seated on filaments 

 which, at a short distance, were septate in a similar manner to the 

 previously examined thread. The whole gathering showed a great 

 preponderance of septate filaments, divided completely, and somewhat 

 constricted at the joints, some of the cells being two, and others 

 three times the diameter or more in length ; filaments which did not 

 bear oogonia, or only one or two, being most divided so that 

 Dr. Cooke was compelled against his first impression to accept the 

 fact that the filaments of this undoubted Vaucheria had been divided 

 off into cells at the period of fructification. 



The question which at once suggested itself was — as to the object 

 of this septation. And here it may be suggested that the single 

 asexual zoospore, produced in small numbers, and the single oospore 

 produced in the oogonium, always has appeared to be a very sparse 

 provision for the reproduction of the species, as compared with the 

 large number of zoogonidia which are produced in every fertile cell 

 of Gladoj)hora and Chcetomorpha. Even in the BotrydiacecB, the 

 multiplex modes of reproduction are strongly in contrast with what 

 has been known as the reproductive process in Vaucheria. For these 

 reasons there does not appear to be any improbability in the supposi- 

 tion that zoogonidia may be produced in Vaucheria, in cells divided 

 off for that purpose. The formation of the cells, the accumulation of 

 the cytioplasm, acquiring density and, as he strongly believes, 

 differentiation, lend strength to the probability that reproduction by 

 zoogonidia may yet be discovered in Vaucheria. No active zoogonidia 

 were detected, but bodies were seen of a definite form, resembling 

 zoogonidia at rest, in the cells ; and in the water in which the 

 gathering was kept were found similar bodies outside the threads, 

 pome in a state of germination. It must not be supposed that the 



