SOME PROBLEMS OF REPRODUCTION. 19 
but the zoospores, formed by the resolution of the protoplasm 
into uninucleated cells, have nuclei constituted by the fusion 
of several vegetative nuclei. We may, however, regard this 
multiple fusion of nuclei as a karyogamic process, and the 
zoospores as zygotes issuing from multiple endogamy. This 
process is a further development of the gametogeny of Dasy- 
cladus; and we shall find that the Saprolegniex and Pero- 
nosporee have similar relations with one another. 
Spo #roptea,! like Cladophora, has chambered filaments, and 
each chamber is subdivided by protoplasmic septa, in which 
alone the nuclei lie, from one to four in each. The plant is 
oogamous. The spermatozoa are formed in distinct chambers 
to the oospheres ; to form the former rapid nuclear fission takes 
place in each protoplasmic septum, which is finally resolved 
into the numerous uninucleate spermatozoa, the parietal 
protoplasm being also used up in the process. 
The oospheres are also formed by the rounding off of the 
protoplasm into numerous uninucleated spheres without epi- 
plasm ; perforations are formed in the wall of the tube to admit 
the spermatozoa, but how or at what stage is not stated. The 
oosphere-nucleus is formed by the fusion of several nuclei. 
Rauwenhoff writes,” “The number of nuclei seems to diminish; 
each aggregation of protoplasm possessing three or four 
chromatophores, . . . . while I only found one or two nuclei. 
When there were two, they were closely appressed; when a 
single one, it was large and elongated. In either case the 
nucleoli had disappeared ; the chromatic elements were visible 
as dots or rods, aggregated in an irregular figure. To all 
appearances, then, several nuclei fuse into one.””? This account 
might almost fit word for word the phenomena seen in the 
formation of the oospheres of Saprolegnia. 
1 «Zur Kenntniss der Algengattung Spheroplea,” in ‘ Berichte d. Deutsch. 
Bot. Gesellsch.,’ vol. i. 
2 “Rech. sur le Spheroplea annulina,” in ‘Arch, Néerland.,’ vol. xxii, 
1888. ‘This later paper I only saw during the correction of the proofs. I 
had, in the MSS., anticipated the probability of nuclear fusion in the 
oospheres, despite Heinricher’s statement to the contrary. 
