168 INTELLIGENT BEHAVIOUR 
whose intelligence can mould behaviour in accordance with 
the new circumstances of a wider life. 
Secondly, this selection of the intelligent involves the 
survival of those in whose higher brain-centres there is room 
for a greater range and variety of interconnection by means of 
associating fibres. It involves a selective survival of the 
larger and more finely organized brains. It is probable, as 
Professor Ray Lankester has recently indicated, that the 
ridiculously small-brained mammals and reptiles of the past 
were creatures of instinct with little capacity for intelligent 
control. Their lives were simple, and their enemies and com- 
petitors no better provided with higher brain-centres than 
themselves. Stereotyped instinctive behaviour sufficed to 
enable them to hold their own, and meet the requirements of 
a life of dull and unprogressive monotony. Strength without 
cunning made these big-framed animals for a while masters of 
the situation. But there are no existing animals, whose 
skeletons indicate so high a position in the zoological series, 
which exhibit a cerebral development so poor. And we may 
fairly conclude that the fact that these huge creatures have 
left no lineal descendants may be taken as evidence of the 
importance and value, in evolution, of that cerebral tissue 
which is the organic basis of intelligence. The higher brain 
contains the potentiality of that experience without which 
the evolution of intelligent behaviour in any race of vertebrate 
animals is impossible. 
V.—TuHE INFLUENCE OF INTELLIGENCE ON INSTINCT 
We have seen thai the relation of instinct to intelligence is 
essentially that of congenital to acquired behaviour. We have 
seen, too, that in the Lamarckian interpretation what is 
acquired in the course of life may be transmitted through 
inheritance, and thus the intelligent behaviour of one genera- 
tion may become instinctive and congenital in the next. But 
serious biological difficulties stand in the way of the acceptance 
