852 ENVIRONMENT AMONG MEN 



youug, and who have been reared exactly ahke up to their early 

 manhood and womanhood. Since then the condition of their 

 lives has changed ; what change of nurture has produced the 

 most variation ? . . . They (the 35 cases) showed me that in 

 some cases the resemblance of body and mind had continued 

 unaltered up to old age, notwithstanding very different conditions 

 of life ; they showed me that in other cases the parents ascribed 

 such dissimilarity as there was, wholly or almost wholly to some 

 form of illness.' ^ ' We may, therefore, broadly conclude that 

 the only circumstance, within the range of those by which persons 

 of similar conditions of life are affected, that is capable of producing 

 a marked effect on the character of adults, is illness or some 

 accident which causes physical infirmity.' ^ Galton then turns 

 to consider the details regarding twenty cases of unlike twins 

 and he finds that in spite of similar surroundings no growing 

 resemblance can be traced.^ 



10. In attempting to sum up our conclusions on this subject, 

 we may first ask what influence is to be attributed to the environ- 

 ment and then ask what bearing such influence has upon the 

 main problem under review in these later chapters. It has always 

 to be recollected that changes in the environment may have the 

 most extreme results. Some examples were given of experiments 

 upon developing animals, and it was shown that in the case of 

 fish, for example, monsters of various kinds can be produced. 

 So too doubtless extreme modifications could be produced in 

 the case of man and are occasionally produced by untoward 

 surroundings and by such customs as those of the distortion of 

 the head and of the feet. What we want to know, however, is 

 not what modifications can be produced, nor what exceptional 

 modifications sometimes arise, but what changes are induced by 

 the variations in the environment which usually occur. 



The answer is that, putting aside disease among the factors 

 and leaving out for the moment temperament among the cha- 

 racters, such variations as occur are of little importance. This 

 appHes to both physical and mental predispositions and includes 

 the effect of not only such factors as climate and so on but also of 

 such factors as are summed up in a good or bad home environment. 



» Galton, Inquiries into Human Faculty, p. 233. » Ibid., p. 235. « Ibid., 



p. 237. The general results of Galton's work have been confirmed in all important 

 respects by Thomdike's elaborate investigations ('Measurements of Twins' 

 Archives of Philosophy, Psychology, and Scientific Methods, vol. i, 1905). 



