264 Proceedings of the Royal Physical Society. 
about the material overflow, the divergence of the sexual 
elements from a common basis has ended in the production 
of countless adaptive modifications and the evolution of 
‘species,’ while the accessory devices favourable to conju- 
gation, which have been slowly and adaptively evolved, 
have led to a gradually intensified expression of passion 
and love, which have become important motive forces in the 
drama of evolution at large.” 
With many of Mr Ryder’s conclusions we must agree. 
Some of them had been already expressed in the “ Evolution 
of Sex.” His insistance on the fundamental importance of 
growth as the great peculiarity of organisms; his interpreta- 
tion of sexuality in terms of nutrition; his protest against 
teleological explanations of facts, ¢.g., of sexuality as a means 
of securing variation; his insistance on the reproductive 
factor in evolution, seem to us in essential agreement with 
what was advanced in the work cited. Moreover, though we 
do not regard the male cell as “ anabolic,” we certainly agree 
with him in seeking for more precise statements as to the yolk 
of ova than are to be found in the “Evolution of Sex,” and 
we agree that “reciprocal assimilation,” or “reciprocal inte- 
gration,” is more accurately descriptive of one of the aspects 
of fertilisation. 
We differ, however, from Mr Ryder on at least three 
important points :-— 
(1) We maintain, with the correction already noticed, the 
general thesis expressed in the “ Evolution of Sex.” 
(2) We regard his general theory as involving too many 
unestablished hypotheses, ¢.g., the preponderance of chromatin 
over cytoplasm in primordial units, the origin of chromatin 
as a metabolic product of the cytoplasm. 
(3) We distrust all conclusions as to physiological facts 
based upon morphological distinctions such as that between 
cytoplasm and nucleoplasm. For if we lay aside all bias, it 
must be confessed that both terms cover vast areas of ignor- 
ance. What is cytoplasm or nucleoplasm? What relation 
does the nucleus bear to cell and its metabolism? Is 
Auerbach right in finding a qualitative difference between 
the chromatin of the sperm and that of the ovum ? 
