Einier on Gro7vth and Inheritance 459 



he speaks ^ of ' inherited definite tendencies ' as alone con- 

 stituting ' the specific qualities of the various species.' But 

 though thus occasionally lapsing into such dynamical 

 expressions with respect to vital actions, he ordinarily 

 follows the prevailing school in relying on mere words as 

 explanations. Thus, he tells us,^ 'it has come about that 

 heredity not only constitutes this unity by development, but 

 also endeavours to reconstitute it after injury.' ' Heredity ' 

 is, of course, a term now current ; but in what is it really 

 clearer or more explanatory than the term nisus fomiativv^'? 

 What is there really more intelligible in his own expressions,^ 

 ' growth tendency ' and 'formative power ' ? Again, he tells 

 us that a mutilated whole is reformed because in each of its 

 particles 'there is something of the tendency to form a whole,' 

 and he speaks of ' a tendency to develop into the whole by 

 ' growth ' being ' impressed upon the several particles of an 

 organism by heredity/ Thus heredity is personified and 

 made an active agent, regardless of the fact that it is a mere 

 abstract term denoting various phenomena. An actual, con- 

 crete, dynamic, immaterial agency, immanent in every living 

 organism, is, however, a conception which (be it true or false) 

 does at least serve to explain the phenomena of growth, 

 repair, development, and phyletic evolution. That processes 

 of repair are not mere processes of vital crystallisation taking- 

 part upon a 'polarised terminal surface' is, to our mind, 

 sufficiently demonstrated by the differences of tissue and of 

 internal arrangements of parts which may be found in a re- 

 formed part, externally like its normal predecessor — as, e.g., 

 in a re-formed lizard's tail. That normal development is due 

 to nothing of the kind is also shown by the fact that in the 

 developing embryo there is no ' polarised terminal surface,' as 

 there is the stump of a tail or limb which has been re- 

 moved. 



1 P. 386. 2 p. 394. 3 p^ 407. 



