Wager . — The Sexuality of the Fungi. 587 
basidium divides up after the nuclear fusion into a number of 
cells, each of which contains one nucleus. In Tremella the 
cell divisions are longitudinal ; in Auricularici they are trans- 
verse. Each cell produces a sterigma, at the apex of which 
a spore is formed, and the nucleus then passes into it. 
This phenomenon of nuclear fusion in the Basidiomycetes 
is regarded by Dangeard as sexual and the basidium as an 
oospore 1 . 
Theoretical Considerations. 
We have now to consider the general bearing of these facts 
upon the question of sexuality. 
Sexual reproduction may be regarded as a process by which 
(1) the energy of division is restored, and (2) two independent 
lines of descent blended into one. 
According to many observers the essential end of sexuality 
is rejuvenescence. The cell in some way becomes enfeebled, 
loses c the capacity of carrying on the vital processes by 
itself 2 / and requires some stimulus to reinvigorate it to 
further growth. Hence the need for fertilization. But 
whether this is a primary attribute of living matter or has 
been secondarily acquired in order to ensure a mixture of 
germ-plasms derived from different sources has not been 
determined 3 . 
A study of the process of fertilization in the Phycomycetes 
lends support to the view that the fusion of the two cells and 
nuclei is primarily for purposes of reinvigoration simply. In 
all the higher forms of life the only mode of reproduction 
is sexual. In the Fungi and lower forms of life generally we 
have in addition asexual reproductive organs, which, as Stras- 
burger says 4 , ‘ are especially concerned with the rapid 
multiplication of the individuals under favourable external 
conditions ; whilst sexual reproduction is of importance in 
1 Dangeard, loc. cit. 
2 Hertwig, The Cell, Eng. edit., p. 291. 
3 See Wilson, The Cell in Inheritance and Development, pp. 129, 130. 
4 Strasburger, The Periodic Reduction of the number of the Chromosomes in the 
Life-History of Living Organisms. Ann. Bot., viii, 1894, p. 282. 
