354 THE POPULAR SCIENCE MONTHLY. 



had expected. They showed me that in some cases the resemblance 

 of body and mind had continued unaltered up to old age, notwith- 

 standing very different conditions of life ; and they showed in the 

 other cases that the parents ascribed such dissimilarity as there was, 

 wholly, or almost wholly, to some form of illness. In four cases it 

 was scarlet fever; in one case, typhus; in one, a slight effect was as- 

 cribed to a nervous fever : then I find effects from an Indian climate ; 

 from an illness (unnamed) of nine months' duration ; from varicose 

 veins ; from a bad fracture of the leg, which prevented all active ex- 

 ercise afterward ; and there were three other cases of ill health. It 

 will be sufficient to quote one of the returns; in this the father 



writes : 



"At birth they were exactly alike, except that one was born with 

 a bad varicose affection, the effect of which had been to prevent any 

 violent exercise, such as dancing or running, and, as she has grown 

 older, to make her more serious and thoughtful. Had it not been for 

 this infirmity, I think the two would have been as exactly alike as it 

 is possible for two women to be, both mentally and physically ; even 

 now they are constantly mistaken for one another." 



In only a very few cases is there some allusion to the dissimilarity 

 being partly due to the combined action of many small influences, and 

 in no case is it largely, much less wholly, ascribed to that cause. In 

 not a single instance have I met with a word about the growing dis- 

 similarity being due to the action of the firm free-will of one or both 

 of the twins, which had triumphed over natural tendencies ; and yet 

 a large proportion of my cori;^spondents happen to be clergymen 

 whose bent of mind is opposed, as I feel assured from the tone of 

 their letters, to a necessitarian view of life. 



It has been remarked that a growing diversity between twins may 

 be ascribed to the tardy development of naturally diverse qualities ; 

 but we have a right, upon the evidence I have received, to go further 

 than this. We have seen that a few twins retain their close resem- 

 blance through life ; in other words, instances do exist of thorough 

 similarity of nature, and in these external circumstances do not create 

 dissimilarity. Therefore, in those cases, where there is a growing di- 

 versity, and where no external cause can be assigned, either by the 

 twins themselves or by their family for it, we may feel sure that it 

 must be chiefly or altogether due to a want of thorough similarity in 

 their nature. Nay, further, in some cases it is distinctly affirmed that 

 the growing dissimilarity can be accounted for in no other way. We 

 may therefore broadly conclude that the only circumstance, within the 

 range of those by which persons of similar conditions of life are 

 affected, capable of producing a marked effect on the character of 

 adults, is illness or some accident which causes physical infirmity. 

 The twins who closely resembled each other in childhood and early 

 youth, and were reared under not very dissimilar conditions, either 



