BIOPSYCHOLOGICAL 66i 



specialisation of function and integration, and in each species on its 

 definite lines to definite form. Yet this process is not automatic or 

 stereotyped, since the embryo may exhibit considerable self- 

 regulation, and vary its development to cope with unusual or adverse 

 circumstances. Development is so far recapitulatory: yet in early 

 development organs are formed in advance of functioning: and as 

 development proceeds, their full differentiation then becomes 

 dependent upon their functioning. Of these two stages of develop- 

 ment the mnemic theory affords a simple solution : organs originally 

 formed in response to particular environmental stimuli may lose 

 their dependence upon the functional stimulus, and appear in 

 ontogeny in response to an associated stimulus, or in the absence of 

 any stimulus at all. The mnemic theory in this way allows for a 

 transmission of acquired characters — and affords also an explanation 

 of recapitulation. From the functional and mnemic view- point, the 

 essential thing in heredity is the transmission of tendencies — virtual 

 or potential functions — and the essential thing in development is the 

 actualisation of these. 



Russell, with the unity and simplicity of his psychobiological 

 treatment, does not apply our distinction of biopsychologic and 

 psychobiologic ; indeed, he may at first sight even disapprove it, 

 as savouring of "dualism", or of "interaction", in the usual senses. 

 For we may seem to be assuming a dualistic separateness as of old 

 between mind and body, yet this with alternate interaction too. 

 In the theory of interaction a bodily stimulus is communicated to 

 the psychic life, which Huxley thus called mere "epiphenomenon" : 

 but we call this whole process, in both aspects, biopsychological. 

 Conversely, when psychic impulse seems antecedent to the material 

 response, though both are again viewed as aspects of a unified 

 process, this we call psychobiological. The notation above employed 

 may so far appear of a dualistic kind, but this is not its intention. 

 Yet its employment in this form at the outset has conveniences, 

 since the very terms biology and psychology have arisen from the 

 apparent distinctness of their respective phenomena and processes ; 

 no one can help using their respective vocabularies; since there is 

 as yet no adequate intermediate or unifying one. 



On this notation, then, the unified character of life is maintained: 

 albeit also with the physiological and psychological distinctness of 

 customary thought. How is the reconciliation possible, and even 

 satisfactory? We habitually view curved surfaces as concave or 

 convex, witness cup and ball, egg and eggcup. Even when the form 

 of a familiar object shows both together as with cup or spoon, it is 

 their concavity which is important: whereas it is the unbroken, 

 full and convex egg which we recognise and select, with little heed 

 of eggshells emptied to concave. Again, viewed from opposite sides 

 of the table, this curve is convex to me, but is primarily concave to 



