DECEMBER 24, 1897. ] 
wholly on lines of Natural Selection. 
Moreover, instincts (and such physical char- 
acters as are analogous to instincts, 7. e., in- 
born physical parts) cannot have resulted 
from the transmitted effects of experience 
and use, since they do not increase under 
such stimulation. There is, for instance, 
no reason to suppose that any instinct is 
sharpened by use, or, in other words, by ex- 
perience. In fact, it would be a contradic- 
tion in terms to suppose that it is, since, if 
my definitions are right, all that is acquired 
pertains to reason, not to instinct. More- 
over, did instincts increase under stimula- 
tion and were this increase transmissible in 
however slight a degree, then instincts 
should be most developed in the highest 
animals and less in lower animals. The 
contrary, however, is the fact.* 
All acquired mental characters depend, 
of course, in the last analysis, on memory ; 
and, therefore, an animal which is incapa- 
ble of acquiring mental characters, and 
which, therefore, depends wholly on in- 
stinct, can have no recollection of past 
events, nor, aS a consequence, any ideas 
concerning the future ; it must live entirely 
in the present. To this it may be objected, 
however, that various insects display an in- 
stinctive memory, and, for instance, return 
again and again with food to the nest where 
they have laid their eggs. If, however, my 
definitions are correct these returns are not 
due to memory, but to an impulse (similar 
to that which causes them in the absence of 
experience to know a fit spot wherein to 
lay their eggs), which causes them again 
and again to return to this particular place, 
quite independently of any recollection of 
having been there before.t It has even 
* Tt follows, then, from the above, that, except as 
regards the effects of mutilations, which I do not here 
consider, evolution can have proceeded only on the 
lines of inborn variations. 
+ Compare the swiftly forgotten alarm of a house- 
fly with the more and more permanent fear of suc- 
cessively higher creatures. 
SCIENCE. 
939 
been denied that animals so high in the 
scale as fish possess a memory (the power 
of acquiring mental characters).* The seat 
of the memory has been held to be the cor- 
tex of the brain, and fish alone of all verte- 
brata have no cortex. I think, however, 
there can be no doubt that fish have some 
power of acquiring mental traits, since trout 
in a much-fished stream soon grow more 
wary. Indeed, memory may be detected in 
animals much lower than the fish. Even 
so low in the scale as the oyster is a rudi- 
mentary capacity for mental acquirement 
observable, for “‘even the headless oyster 
seems to profit from experience, for Dic- 
quemase asserts that oysters taken from a 
depth never uncovered by the sea open their 
shells, lose the water within and perish; 
but oysters taken from the same place and 
depth, if kept in reservoirs, where they are 
occasionally left uncovered for a short time 
and are otherwise incommoded, learn to 
keep their shells shut, and then live for a 
much longer time when taken out of the 
water.’ { 
As I have already said, speaking in gen- 
eral terms, the higher placed an animal is in 
the scale of life the greater is its power of 
acquiring mental characters, as will be ap- 
parent presently and as might have been 
expected ; but it is also true that the higher 
species of a lower class or order often ex- 
hibit greater capacities for acquirement than 
* Vide Lancet, January 23, 1897. 
} And, therefore, in choosing the dragon-fly as an 
animal conspicuously lacking in acquired mental 
traits to contrast with man, in whom they are con- 
spicuously abundant, I have not intended to imply 
that the former is quite incapable of acquiring men- 
tal characters, only that it is so little capable of ac- 
quiring them that it forms an admirable foil to man, 
the animal above all the most capable of such ac- 
quirement. I do not know that the dragon-fly is 
quite lacking in this quality, but only that it is so 
little developed in him that I personally, with my 
imperfect knowledge, have not been able to detect 
any traces of it. 
{‘ Animal Intelligence,’ by Romanes, pp. 24, 25. 
