of Peronospora parasitica. 265 
In 1889 1 I showed that in Peronospora parasitica both 
oogonium and antheridium are multinucleate; that previous 
to the differentiation of the oosphere the nuclei of both these 
organs undergo mitosis ; that in the separation of the oosphere 
from the periplasm the majority of the nuclei of the oogonium 
pass into the periplasmic layer, and that finally the oosphere 
when ready for fertilization contains only one nucleus. 
The exact details of the fertilization were not investigated, 
but the following conclusion was arrived at from a considera¬ 
tion of the facts observed: ‘ The passage of a nucleus from the 
antheridium into the oosphere has not been directly observed, 
but it is probable that fertilization does take place, as two 
nuclei have been seen in the oosphere at about the time when 
a nucleus or nuclei from the antheridium appear to pass over 
into the fertilizing tube.’ 
Istvanffi 2 , in 1889, described the oogonia and antheridia of 
Cystopus Portulacae as multinucleate, and referred to the 
process of fertilization as consisting probably in the fusion 
of the nuclei of the two sexual organs. ‘Die Befruchtung 
erfolgt auch hier hochst wahrscheinlich nur durch die Ver- 
mischung der Zellkerne beiderlei Sexualorgane.’ 
In 1894 Dangeard 3 made some observations on Pythium 
monospermum Prings. and P. proliferum De Bary, in which 
he showed that the antheridia and oogonia are multinucleate. 
He also pointed out that a central oleaginous globule appears 
in the oogonium at a certain stage, and that this was probably 
mistaken by Fisch for a nucleus and led him to the conclusion 
that all the nuclei of the oogonium fused together to form 
a single sexual nucleus. 
Dangeard also found that the antheridia and oogonia are 
multinucleate in C. Candidas , C. cubicus , Plasmopara nivea , 
and P. densa. He was unable to observe any details of 
1 Wager, On the Nuclei of Peronospora parasitica, &c„, Ann. of Bot., vol. iv, 
p. 127. 
2 A peneszek sejtmagavrol (De fungorum nucleis). Magyar Novenytani Lapok, 
xiii, 1889, pp. 33-46. See Ueber die Rolle der Zellkerne bei der Entwickelung der 
Pilze, Ber. d. deut. Bot. Gesell., Nov. 1895, p. 437, 
3 loc. cit. 
