402 THE STUDY OF ANIMAL LIFE CHAP. 



does seem to be inherited, however, is a defectiveness 

 or disturbance or degeneracy of the germ-plasm which 

 may find one expression in the parent and another in the 

 offspring, or the same in both." 1 



The student should recognise that the long-drawn-out 

 discussion on the transmission of somatic modifications 

 can only be settled by the critical accumulation of facts. 

 There should be no attempt to close it or to dogmatise 

 about it. As Prof. E. B. Wilson has wisely said : " In 

 the present defective state of our knowledge we may 

 well grant that there may be many a thing between 

 germ-cell and body that is not yet dreamed of in our 

 biological philosophy." 



4. The Importance of Nurture. If individually acquired 

 modifications due to peculiarities of function and environ- 

 ment are not transmissible, it docs not appear at first sight 

 that nurture can be of much evolutionary importance to 

 the race. This is confirmed as regards man by the 

 statistical inquiries which have led Prof. Karl Pearson 

 and his collaborators in the Galton Laboratory to the 

 important conclusion that the results of changes in nur- 

 ture are of relatively small importance compared with 

 the results of variation in the physique, the mentality, 

 and the habits of parents, that " the degree of depen- 

 dence of the child on the characters of its parentage is 

 ten times as intense as its degree of dependence on the 

 character of its home or uprearing." ' It is five to ten 

 times as profitable for a child to be born of parents of sound 

 physique and of brisk, orderly mentality, as for a child 

 to be born and nurtured in a good physical environment." 

 But while there is no doubt as to the fundamental im- 

 portance of the inherited nature, there is also importance 

 in nurture. 



(1) Since nature and nurture are both indispensable, 

 there is no antithesis. Some creatures are indeed so strong 

 that changes of nurture do not seem to matter very 

 much, so long as the essential conditions of life arc not 

 interfered with ; in many other cases, however, the 



1 See the author's Darwinism and Human Life, revised edition. 

 Melrose, London, 1916. 



