2 68 Habit and Instinct. 



function ; more than this, it has neither the energy nor 

 the opportunity for doing ; and any organism in which it 

 failed to do this would inevitably succumb and suffer the 

 stern fate of elimination. 



Thus in the many and various inter-relations and 

 inter-dependencies of animals with reference to each 

 other, and to their inorganic environment, the mental 

 system of any individual must be of such a kind as to give 

 opportunities for choice and control by which the needs of 

 organic life may be met, and adjustments made in relation 

 to these needs. For this experience affords the data. 

 Experience brings the animal into more extended touch 

 with its surroundings than is possible in the merely 

 organic phase of life-progress. And if the expression of 

 emotions has suggestive value, experience also brings the 

 animal into wider touch with other animals. The horse 

 reacts to the varying moods of its companions ; the lonely 

 chick restored to its fellows no longer utters its querulous 

 note of complaint. All this has reference to the develop- 

 ment of the more or less complex mental system of any 

 animal; and so far we are regarding the mind of the 

 creature as a whole, just as we regard its body as a whole. 

 There is, however, another aspect of organic evolution 

 that must be clearly grasped and steadily borne in mind. 

 As there is a delicate and intricate inter-dependence of 

 organic forms, so that no individual is isolated, but must 

 adjust itself to a complex environment of other individuals 

 of its own kind, and of other species in varying degrees, 

 so too within the organism every constituent particle or 

 cell is in more or less close relationship with all the 

 others that are incorporated in the same bodily system. 

 Take, for example, a secreting cell in one of the glands, 

 the products of which minister to digestion. It plays 

 its part in the nourishment of the whole body. But 



