578 Wager . — The Sexuality of the Fungi . 
in which the fusion of sexual nuclei does not occur until 
a much later stage, subsequent division of the zygote-nucleus 
does not take place, so that the ripe zygote contains only 
one nucleus. 
This difference in the behaviour of the nucleus during the 
maturation of the oospore is probably connected with the 
mode of germination. De Bary 1 has already pointed out 
that in Cystopus and some other species the oospore on ger- 
mination produces at once a mass of zoospores. In Pero- 
nospora Valerianellae and others the oospore at once develops 
a germ-tube. It may be therefore that the uninucleate con- 
dition of the zygote indicates germination by a germ-tube, 
the multinucleate condition germination by the formation 
of zoospores. 
In the Saprolegnieae it has not been found possible to 
obtain perfectly satisfactory information as to the nature of 
the sexual process. According to the views of De Bary 2 , 
Marshall Ward 3 , Hartog 4 and others, the antheridial tube 
never opens into the oosphere, although it becomes firmly 
attached to it. Trow 5 , on the other hand, maintains that 
in some species at any rate a true fertilization occurs by 
the passage of a nucleus into the oosphere. The facts 
which he brings forward to support his view are : ( 1 ) The 
young oosphere at first contains only one nucleus. At 
a later stage two are to be found. (2) These two nuclei 
fuse together into one, the embryo-nucleus. (3) In one case 
the apex of an antheridial tube containing a nucleus was 
observed penetrating the oosphere. (4) The second nucleus 
of the oosphere appears at an early stage just beneath the 
wall of the oosphere, and in close proximity to the anthe- 
ridial tube outside. 
From my own observations I am able to confirm (1), (2), 
1 Fungi, Eng. edit., p. 135. 
“ De Bary, Fungi, Eng. edit. 
a Marshall Ward, loc. cit, p. 272, also Q. J. M. S., 1883. 
4 Hartog, Cytology of the Veg. and Rep. Organs of the Saprolegnieae. Trans. 
R. Irish Acad., vol. xxx, 1895. 
Trow, Ann. of Botany, ix, 1895, and xiii, 1899. 
