EVOLUTION OF INTELLIGENT BEHAVIOUR 155 
of the animal are predominantly intelligent, I am far from 
wishing to assert dogmatically that in no animals are there 
even the beginnings of a rational scheme. Indications thereof 
do not indeed at present appear to have been clearly disclosed 
by experiment. But the experimental development of the 
subject is still in its infancy. We shall probably have to await 
the further results which must be the outcome of patient and 
well-directed child-study. The human child does pass in the 
course of his individual development from intelligent to 
rational procedure. Here there is a bridge which is crossed 
by every child. When we know more about the stadia of this 
development we shall be in a position to apply the results 
obtained in child-study in the analogous field of animal-study. 
Till then we must possess our souls in patience, and base our 
provisional conclusions on the results of systematic investiga- 
tion, rather than on those of casual observation and anecdote. 
IV.—Tue Evouvution or INTELLIGENT BEHAVIOUR 
It is difficult to say where, in the hierarchy of animal 
progress, the beginnings of intelligence can first be traced. In 
the articulated animals, such as the insects, spiders, and 
crustacea, there is abundant evidence of intelligence of a 
relatively high grade. Many molluscs unquestionably profit 
by experience. The way in which limpets return to the scars 
on the rock which form their homes seems to show that they 
have acquired a practically adequate experience of their near 
surroundings. Romanes cites * some of the earlier observa- 
tions which were extended by Professor Ainsworth Davis.t I 
looked into the matter myself some years ago, at Mewps Bay 
near Lulworth in Dorsetshire. The method adopted f was to 
remove the limpets from the rock, and affix them at various 
distances from their scars. This can be done without difficulty 
or injury to the mollusc if one catches them as they are moving. 
* « Animal Intelligence,” pp. 28, 29. t Nature, vol. xxxi., p. 200. 
t Ibid., vol. li., p. 127. 
