No. 460.] STUDIES ON PLANT CELL—V. 243 
modia live. It is quite possible that the origin of sex may have 
been involved with some of the same principles as those which 
bring about the union of swarmers to form a plasmodium, but 
the added features of nuclear fusion together with the history 
of the sexually formed cells which become in higher groups the 
starting point of a sporophyte generation places the sexual act 
on a very much higher level of complexity. 
There are some records of the union of several zoöspores or 
gametes to form a zygospore instead of the usual conjugation in 
pairs. The biciliate gametes of Acetabularia (De Bary and 
Strasburger, '77) sometimes conjugate in threes and large 
zygotes are figured with five pairs of cilia indicating that as 
many gametes entered into their formation. The gametes of 
Protosiphon, described by Rostafinski and Woronin (77) as in 
the life cycle of Botrydium, are reported by them to unite at 
times several together and four are so figured. Klebs ('96, p. 
207) in his account of Protosiphon also noted the union of the 
gametes in threes especially when in organic solutions. The 
significance of these multiple fusions of swarm spores is not 
clear for we know nothing of the nuclear history following the 
union. There is in the habit, however, such a resemblance to 
the extensive union of swarmers in.the Myxomycetes as to indi- 
cate that primarily sexuality may have been concerned chiefly 
with cytoplasmic fusions and associated very intimately with 
nutritive processes. have recently observed several instances 
of the conjugation of zoóspores of Saprolegnia when the ele- 
ments united in pairs at the ciliated ends and along the sides 
exactly as do motile gametes, and the fused cell bore four cilia. 
The zoóspores of Saprolegnia are too far removed morphologi- 
cally from the highly differentiated sexual organs of the group 
to justify the explanation of such conjugation as a sexual act. 
and we must think of it as due to some peculiarities of nutritive 
conditions. 
Another class of very interesting cell fusions, associated with 
nutritive functions, is presented in the union of the sporophytic 
fertile filaments (oóblastema filaments) in the cystocarp of the 
Rhodophycez with auxiliary cells. This phenomenon which 
was regarded by Schmitz and his followers as sexual in charac- 
