** Mental Evolution in Animals” 57 
grows his body as he does, anda bird makes her nest as she 
does, because both man and bird remember having grown 
body and made nest as they now do, or very nearly so, on 
innumerable past occasions.” He thus, as I have said on 
an earlier page, reduces life from an equation of say 100 
unknown quantities to one of 99 only by showing that 
heredity and memory, two of the original 100 unknown 
quantities, are in reality part of one and the same thing. 
That he is right Mr. Romanes seems to me to admit, 
though in a very unsatisfactory way. 
What, for example, can be more unsatisfactory than the 
following ?—Mr. Romanes says that the most fundamental 
principle of mental operation is that of memory, and that 
- “is the conditio sine quad non of all mental life” (page 
35)- 
I do not understand Mr. Romanes to hold that there is 
any living being which has no mind at all, and I do under- 
stand him to admit that development of body and mind 
are closely interdependent. 
If, then, ‘‘ the most fundamental principle ” of mind is 
memory, it follows that memory enters also as a funda- 
mental principle into development of body. For mind and 
body are so closely connected that nothing can enter 
largely into the one without correspondingly affecting 
the other. 
On a later page Mr. Romanes speaks point-blank of the 
new-born child as ‘‘ embodying the results of a great mass 
of hereditary experience’’ (p. 77), so that what he is driving 
at can be collected by those who take trouble, but is not 
seen until we call up from our own knowledge matter whose 
relevancy does not appear on the face of it, and until we 
connect passages many pages asunder, the first of which 
may easily be forgotten before we reach the second. There 
can be no doubt, however, that Mr. Romanes does in 
reality, like Professor Hering and myself, regard develop- 
ment, whether of mind or body, as due to memory, for it is 
