BawpeEN, Psychological Theory of Evolution. 275 
This same food problem may be stated in another way. 
The instinct of hunger, as SPENCER has pointed out, lies at the 
basis of the development of intelligence, as that of sex (in the 
broad sense) lies at the basis of social organization. The nutri- 
tive function as it develops implies three things wherever the 
problem becomes at all complex. It involves, first, the recog- 
nition of the distant food object, secondly, movement toward 
it, and thirdly, the oral or manual manipulation of it when 
reached. With the appearance of the multicellular form the 
growth of definite organs for the perception and securing of 
food not immediately at hand becomes a prime necessity. The 
multicellular animal probably originated asa sessile form on 
elevated areas of the ocean bottom where an abundance of food 
obviated the necessity that each cell should lead an independent 
existence in the struggle for life. But as the growth of the 
sessile form exceeded the resources of the immediate environ- 
ment to supply nourishment for the increasing number of cells, 
it became necessary for free moving forms again to develop. 
Slow moving spherical forms like the Medusa, or Jelly-fish, 
probably represent the first stages. More rapidly moving forms 
would tend to take on an elongated shape, bilaterally symmet- 
rical, and later, as definite organs for apprehending and dealing 
with the distant object develop, we get the appearance of dis- 
tinct head and tail ends in the animal. As has been seen, there 
is no necessity for the plant to develop special sense organs or 
organs of locomotion, since the sources of its food are found 
in the soiland air which immediately surround it. But the 
animal must develop such organs or perish. And the develop- 
ment of these organs means the development of intelligence. 
The recognition of the distant object involves the psycho- 
genesis of the various senses, most of which finally come to be 
massed in the head. The first sense imagery to develop, natur- 
ally, would be the tactile imagery, because it was first and most 
closely associated with all the vital processes of the food func- 
tion. The first tactile imagery was doubtless that developed 
in connection with the ingestion of the food object and, from 
the standpoint of the food process, all the other senses and 
