940 
the lower species of a higher class or order. 
It is even true that some invertebrates 
exhibit far greater mental receptivity than 
many vertebrates. Speaking again in gen- 
eral terms, the power of acquiring mental 
characters is only developed to a consider- 
able extent in such animals as tend their 
young, and in them it is developed in pro- 
portion to the length of time parental care 
is continued. Furthermore, it is developed 
to a very great extent only among such 
animals as not only tend their young for 
prolonged periods, but also lead gregarious 
lives. When animals, after laying their 
eggs, abandon them to chance it is clear in 
cases where mind (7. e., consciousness and 
all that results from consciousness) plays a 
part in securing survival that such mind 
must be considerably developed from the 
moment of hatching. Hence it is that in 
such animals instinct greatly predominates. 
Moreover, they cannot acquire traits by 
imitation from their parents, and, therefore, 
whatever is acquired by the one generation 
is completely lost to the next; in other 
words, they have no traditional knowledge, 
- and all that is mental in the individual is 
either inborn or has been discovered by 
himself. But when the animal, after birth, 
is protected for a prolonged period by its 
parent it is clear that instinct (inborn 
knowledge and ways of thinking and act- 
ing) becomes less necessary for survival, 
since an opportunity is afforded for acquir- 
ing fit knowledge and ways of thinking and 
acting from the environment, particularly 
from the parent. It is then possible for 
knowledge to become traditional, and to be 
handed down from parent to offspring. 
When, in addition, such animals lead gre- 
garious existences the individual has the 
‘opportunity of acquiring mental characters, 
not only from the parent, but from other 
members of the community as well, and 
then complex mental acquirements have 
the best chance of being transmitted, in- 
SCIENCE. 
[N. 8. Vout. VI. No. 156. 
stead of being lost. Under such circum- 
stances the power of acquiring useful 
mental characters becomes a main factor in 
the struggle for existence, and those in- 
dividuals that most possess it survive in 
the greatest numbers; and therefore, con- 
currently with the growth of knowledge, 
occurs an evolution of the power of acquir- 
ing knowledge and a corresponding retro- 
gression of instinct, which, in the ancestry, 
was a main factor of survival, but is now 
no longer so. : 
I have given the dragon-fly as an example 
of an active animal which does not tend 
its young, and in which, therefore, instinet 
is developed to a high degree. The ant, on 
the other hand, is an animal which not 
only tends its young, but also lives in great 
communities; and we have striking evi- 
dence that some species of ants, at least, 
and probably all of them, are actuated 
largely by knowledge and motives which: 
are acquired, 7. ¢., by reason, and not by 
inborn mental characters, 7. ¢., by instinct. 
Thus enslaved ants, captured as pups and: 
educated wholly by their captors, differ 
markedly from the free members of the 
species; they have other knowledge and 
ways of thinking and acting; and the fact 
that the slaves, in their new homes, so 
readily adapt themselves to the changed 
environment, so readily exhibit knowledge: 
and ways of thinking and acting which 
must be acquired and cannot possibly be 
instinctive, for the reason that their an- 
cestry can never have been subjected to the 
influence of a like environment, proves how 
great a share reason has in all that is men- 
tal in them. And since the slaves clearly: 
acquire mental traits which fit them for 
their duties as servants, it is not unreason- 
able to suppose that the slave-holders, 
in like manner, individually acquire the 
mental traits which fit them for functions 
as masters, %. e. that in them the slave- 
holding habit is not instinctive, but rational. 
