C. W. SOAL 
170 
Here again we are dealing with biological phenomena of one type. 
It serves no useful purpose to attribute the simpler cases of functional 
adaptation to the direct physiological effect of physical conditions 
upon the organism, as we cannot at present interpret the normal 
process of development in physiological terms. All that we are 
entitled to say on empirical biological grounds is that the limiting 
environmental factors having changed, the type of reaction-complex 
conforming to somatic equilibrium has also changed, but the actual 
observed sequence of events still remains an intrinsic property of the 
organism. In the most complex examples, there is, moreover, some 
evidence that somatic readjustments may take place independently 
of changes in the primary environment. 
III. Let us now consider the bearing of the foregoing discussions 
on the problem of racial development. All evolutionary theories 
recognise that variations are transmitted through the medium of 
the germinal cycle in normal inheritance, but they differ in their 
explanation of how germinal variations originate. There are two 
main divergent points of view on this subject: (1) the Lamarckian 
theory of functional inheritance; (2) theories which rest upon the 
assumption that germinal variations are spontaneous, i.e. not in any 
way conditioned by the course of events in the rest of the organism. 
We shall consider first certain aspects of the second-hypothesis. 
Spontaneous variations are frequently classed as continuous and 
discontinuous, but a much more important difference is between 
those which are fortuitous, or individual in character, and determinate 
variations which are generally attributed to a specific property of 
the germ-plasm. The Darwinian theory, which ascribes specific 
divergence to a differential extinction of individuals in the struggle 
for existence, is equally applicable to minute continuous variations 
and to sporadic individual mutations of larger extent if they are 
hereditarily transmissible. It has been shown, however, by genetic 
experiments that the observed individual fluctuations which formed 
the original inductive basis of this theory are incapable of hereditary 
transmission, and therefore of having any cumulative effect upon 
specific type. The normal phenomena of heredity seem, moreover, 
to imply the existence of some stabilising factor in the germinal 
cycle which does not generally permit any serious modification in the 
properties of the cell. Whether this factor is regarded as an intrinsic 
“chemical stability” on the part of the germinal complex, or a 
particular “quality” of the activity of cell-division, it does not seem 
very consistent with the view that any and every property of the 
