104 THE FIRST PRINCIPLES OF HEREDITY 



embryo-in-being either before or after birth. But in addition 

 to this, the deleterious influence of parental conditions may 

 affect the germ-cells themselves. It is only too apparent 

 that slow poisoning or chronic wasting of the body is bound 

 to react on the germ-cells in an injurious manner. But while 

 it must be admitted that the germ-cells may in a general 

 way become deteriorated through these conditions, leading 

 to under- or mal-development of the germ, there is no reason 

 why such effects should repeat exactly the results wrought 

 in the parent. 



(g) EXTERNAL OR SOCIAL INHERITANCE. 



We now come to the final argument brought forward by 

 the adherents of the positive side for the inheritance of 

 acquired characters. They point, and apparently with 

 some show of justice, to the effects of culture and learning, 

 not only on the individual, but on the generations following, 

 ascribing the moral and intellectual progress of civilization 

 to the transmission of these very qualities acquired by the 

 parents. But here once more it has yet to be proven 

 whether these characteristics, though admittedly acquired, 

 can be said to be inheritable in the true sense. There is a 

 great mass of opinions, feelings, and thoughts handed down 

 from age to age, each generation receiving from the 

 previous one, and standing, as it were, on its shoulders ; but 

 whether such mental experiences become, as Spencer would 

 have us believe, ingrained into the individual consciousness 

 in other words, whether such experiences are inherited 

 biologically is just the point at issue. To try to prove 

 the inheritance of acquired characters from cases where 

 the inheritance itself is doubtful is evidently futile. Indeed, 

 we may look upon the transmission of these social acquire- 

 ments as merely an external one, a handing down of 

 customs, conventions, etc., from generation to generation, 

 which does not necessarily imply any intrinsic change in 

 the mental and moral qualities of the people. " The 



