Cytology of Pythium ultimum, n. sp. 307 
Saprolegnia , and M onoblepharis , with algal ancestors of the 
type of Sphaeroplea , Vaucheria , or Oedogonium. 
It may not be superfluous to add that whatever view may 
be taken of fertilization— whether it is regarded as a means 
of rejuvenescence or as the source of an indefinite number of 
fortuitous variations — the two types present in the Perono- 
sporaceae are of almost equal efficiency. 
It is noteworthy that Harper (’00) has just published an 
account of the fertilization-processes in Pyronema which 
serves to confirm to a considerable extent the hitherto unique 
observations of Stevens, and even perhaps to strengthen 
De Bary’s view of the affinity between the Ascomycetes and 
Peronosporaceae. 
Harper (’ 00 , p. 380), however, does not appear to have 
grasped the significance of the facts published by Stevens, 
for he points out that the multinucleate conidia of Cystopas 
are not called ‘compound,’ although from analogy with the 
multinucleate oosphere that might have been expected. There 
is a very curious confusion of ideas here, from which Stevens 
himself is not exempt, if it be true, as Harper states, that 
he makes use of the term ‘compound antheridium.’ I have 
not been able, however, to trace this term to Stevens. The 
homologues of the oospheres are the sperms and zoospores, 
not the antheridia and sporangia. The conidia of Cystopus 
are sporangia, having indeed a considerable output of zoo- 
spores. The sporangium in this case has retained its 
characteristic power of producing zoospores, but acquired in 
addition a special capacity for dissemination. The antheridium 
and oogonium have, however, developed along different lines. 
The sperms which pass into the oosphere of Cystopus Bliti 
might collectively be called the compound sperm, just as the 
more definitely differentiated oosphere is called the ‘ compound 
oosphere.’ To put the matter more plainly still, if De Bary’s 
view of a gonoplasm could be shown to be true, and the 
gonoplasm were multinucleate, the gonoplasm would be a 
compound sperm. Similarly the conidium of Pythium is, 
phylogenetically considered, a compound spore. Stevens’ 
X a, 
