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place, and the results of which are fortuitous only in the 
sense that some of them may happen to coincide with 
the needs of the animal in its attempt to adapt itself to 
changed conditions. Mr. Spencer refers his fortuitous 
variations to “ the mixtures of constitutional proclivities,” 
but it is probable that constitutional proclivities have 
arisen by the direct action of outward conditions. And 
inasmuch as these proclivities are said to be made more 
and more unlike by unlikeness of physical conditions, it 
would seem probable that the cause which augmented 
the differences, was also the cause which originated them. 
But if this is so, the variations are not the variations 
on which Natural Selection is supposed to act. Moreover, 
if there are two sources of variation, the direct influence 
of the medium acting on similar organisms in a similar 
manner, and the Natural Selection of “ fortuitous varia 
tion, the former will be the most potent factor. Organisms 
are adapted by the circumstances to the circumstances, 
and Natural Selection is not required. 
It may be questioned whether, in the simplest cases of 
conjugation, or the union of the contents of two unicellular 
organisms, there is necessarily any development of those 
variations which are necessarily associated with the sexual 
reproduction of higher animals. It was at one time sup 
posed that the simplest forms of life reproduced themselves 
by fission only; and that the race, like Mr. Besant’s 
Ten Years’ Tenant, was immortal, barring accidents. But 
it has been shown that such fission can only go on for 
a certain time, and that conjugation is necessary after 
a given period to restore the vigour of the race. 
“ In November, 1885, Maupas isolated an Infusorian (Stylonichia), 
and observed its generations till March, 1886. By that time there 
had been two hundred and fifteen generations produced by ordinary 
division, but since these lowly organisms do not conjugate with near