Wager . — The Sexuality of the Fungi. 577 
contains no nuclei. In the central part of the gonoplasm 
a dense, deeply stainable substance then appears, sometimes 
spherical, sometimes irregular in outline, which is regarded 
by Swingle 1 as a definite organ or organoid of the cell, but 
which appears to be nothing more than a condensation of 
granular protoplasm 2 . As soon as it has been produced, 
one of the nuclei from the periplasm passes into the gono- 
plasm, and comes into contact with the central body. In 
Peronospora parasitica 3 this nucleus becomes slightly elon- 
gated in the direction of the central mass before it reaches it, 
and sometimes several of the nuclei in the periplasm exhibit 
a slight elongation in the same direction, so that it is possible 
that the central mass exerts some attractive power on the 
periplasmic nuclei, resulting in the passage of one of them 
bodily through the gonoplasm to come in contact with it. 
The antheridium puts out a fertilizing tube, into which one, 
or perhaps two nuclei pass ; this tube then penetrates the 
periplasm and passes through the gonoplasm until it comes 
nearly into contact with the female nucleus ; and then through 
an opening at the apex of the fertilizing tube, the male 
nucleus makes its way into the gonoplasm, and comes into 
close contact with the female nucleus. The two nuclei may 
at once fuse to form the zygote-nucleus ( Cystopus Candidas , 
C. Portulacae , Peronospora Ficariae , &c.) ; or the fusion may be 
delayed for some time, until the thick membrane surrounding 
the zygote has been partly formed (. Peronospora parasitica). 
The zygote-nucleus, of those species in which the fusion 
of the sexual nuclei takes place at an early stage, begins at 
once to divide, and this division is repeated until as many 
as thirty-two nuclei may be formed ; and in this condition it 
enters on its period of rest. The ripe zygote is therefore 
multinucleate 4 . In Peronospora parasitica , on the other hand, 
1 W. T. Swingle, Two New Organs of the Plant Cell. See Bot. Gazette, Feb. 
1898, p. no. 
2 Wager, loc. cit., 1896. 
3 The following observations on P. parasitica are from an unpublished paper by 
the writer. 
4 Wager, loc. cit., 1896; Berlese, loc. cit. 
