388 REFLEX ACTION, INSTINCT, AND REASON 



thought and intellect, intelligence and reason. But the fact 

 remains that all these faculties are products of evolution, means by 

 which individuals and races are adapted to their environments. 

 They all arose from small beginnings, and increased gradually with 

 the needs of the species as its relations with the environment 

 grew more and more complex. Sensation followed reflex 

 action, instinct followed sensation, memory followed instinct, and 

 intelligence memory. 



645. The mental traits sensations, desires, instincts, memory, 

 intelligence fit in exquisitely with the physical traits skin, bone, 

 blood-vessel, nerves, reflexes, and all the rest. In mind and body 

 the living animal is an immensely complex and wonderfully 

 adjusted machine a machine vastly more complex and perfectly 

 adjusted than anything that has ever been invented by man as the 

 work of his hands and brain. A single important adaptive change 

 in this machine cannot occur separately. It must involve a 

 thousand or ten thousand readjustments, a thousand correspond- 

 ingly important changes in mind and body. Thinking of all this, 

 we realize the full force of the statement that the organism is a 

 bundle of adaptations and co-adaptions. We realize also the full 

 force of the main objection to the mutation theory. It is possible 

 to accept that theory if we think only of such things as the colours 

 and shapes of leaves, or other changes which do not necessarily 

 ruin co-adaptation. But when we take the whole of the facts 

 into consideration, when we think of the complex way in which 

 the mental and physical adjustments of the higher animals inter- 

 lock and how fine the adjustment is, we are driven to the conclusion 

 that evolution can have been founded only on the continual 

 selection and blending of multitudes of small variations, by means 

 of which all co-adapted parts underwent change together, and the 

 organism was moulded as a whole. In other words, we are forced 

 to believe that nature selected for survival, not individuals who 

 varied widely from the rest of the species in this or that particular, 

 but individuals who varied comparatively little as regards the 

 size of their variations, but much as regards the number of their 

 variations, and who, therefore, were better adapted on the whole 

 to the gradually changing environment than their fellows that 

 perished ; and who blended their variationSj so that it was not so 

 much the successful appeal of the individual that counted in the 

 racial struggle for persistence, but the experience of the entire 

 species or variety. Indeed, notwithstanding the wealth of material 

 furnished by fluctuations, so vast is the complexity of the higher 



