572 
Mr. Spencer points out the extreme difficulty of sup 
posing that this process could have been initiated by 
Natural Selection :— 
“ The process is not one to have been anticipated as a result of 
Natural Selection. After numbers of spontaneous variations had 
occurred, as the hypothesis implies, in useless ways, the variation 
which primarily initiated a nervous centre might reasonably have 
been expected to occur in some internal part where it would be fitly 
located. Its initiation in a dangerous place, and subsequent migra 
tion to a safe place, would be incomprehensible. Not so if we bear in 
mind the cardinal truth above set forth, that the structures for holding 
converse with the medium and its contents arise in that completely 
superficial part which is directly affected by the medium and its 
contents ; and if we draw' the inference that the external actions 
themselves initiate the structures, these once commenced and 
furthered by Natural Selection, where favourable to life, would form 
the first term of a series ending in developed sense organs and a 
developed nervous system.”—(p. 67.) 
Elsewhere he says :— 
“Doubtless Natural Selection soon came into action, as, for 
example, in the removal of the rudimentary nervous centres from the 
surface ; since an individual in which they w'ere a little more deeply 
seated would be less likely to be incapacitated by injury of them. 
And so in multitudinous other ways. But nevertheless, as we here 
see, Natural Selection could operate only under subjection. It could 
do no more than take advantage of those structural changes which 
the medium and its contents initiated.”—^. 69-70.) 
We have now to consider how far Mr. Spencer is justi 
fied in supposing that there was a point in which Natural 
Selection interposed. Let it be observed that, in his 
opinion, the process was not initiated by Natural Selec 
tion; that the action of the medium continued throughout 
the whole process of development; and that “Natural 
Selection could only act under subjection. It could do no 
more than take advantage of those structural changes 
which the medium and its contents initiated.” 
Now, in the first place, let us once more remember that 
Mr. Spencer maintains that the hypothesis of Natural