370 REFLEX ACTION, INSTINCT, AND REASON 



thing in nature out of which it was evolved, a thing outside the 

 range of our perceptive powers, then that thing was not mind in 

 any real sense any more than nitrogen and other chemical 

 elements are muscle. 



6 1 1. Granting that mind is a product of evolution, that it 

 originated in connection with movement, and that it occurs only 

 in connection with nervous tissue, to me it seems probable that 

 the order of evolution was as follows. First, through Natural 

 Selection, cells, the function of which was contraction and without 

 which movement would have been impossible, appeared in multi- 

 cellular organisms. Many unicellular organisms are contractile, 

 and some have contractile flagella. Doubtless the contractility 

 of the cells of the higher types was derived from [them. Next, 

 as animals became larger and more complex, as other cells under- 

 went differentiation, as the masses of the cells which were 

 contractile increased in size, number, and complexity, a nervous 

 system was evolved, which consisted of lines of communication 

 (nerve fibrils) and one or more central ganglia. The ganglia 

 received stimuli through the ' afferent ' fibrils from the surface, 

 and translated them into other stimuli which passed outwards 

 through the ' efferent ' fibrils and awakened the activities of various 

 other cells, especially the contractile cells. The function, therefore, 

 of nervous cells was to co-ordinate the reactions of the organism 

 and so adapt it to the environment. Next there were evolved on 

 the surface, at the ends of the nerve fibrils, organs which delicately 

 discriminated between different classes of stimuli light, heat, 

 contact with foreign bodies, and the like. Nerve currents, passing 

 from these surface organs, were transmuted in the ganglia into 

 appropriate stimuli for the several masses of contractile and other 

 cells. As yet there was no consciousness. 



612. Next, the surface organs which received stimuli from the 

 environment evolved into sense organs, where originated nerve 

 currents that gave origin in the ganglia to sensations delicately 

 discriminating stimuli which indirectly (through the efferent nerve 

 currents to which they gave rise) exploded the right stores of 

 energy latent in this or that mass of contractile cells. Throughout 

 the process was one of increasing adaptation to the environment. 

 Thus mind dawned. It will be noted that here I attempt nothing 

 more than a description of the conditions under which, as I 

 suppose, mind appeared. I indicate when, not how, it appeared. 

 I do not know how nervous tissue does this work. I only suppose 

 that it was rendered possible to nervous tissue through the selection 



