Nabours: Promises and Limitations of Eiio-enics 



285 



sunied A was not really 1> and vice 

 versa. Other incidents range from 

 nine cases of a tw^in seeing- his or her 

 reflection in a lookino--glass and ad- 

 dressings it in the belief that it was 

 the other twin in person, to the dif^- 

 cultv which children found in distin- 

 guishing-, in one case, a mother from 

 her identical twin sister, and another 

 case, a father from his identical twin 

 brother. 



In Galton's own words : 



Among my thirty-five detailed cases of 

 close similarity, there are no less than 

 seven in which both twins sufifered from 

 some special ailment or had some excep- 

 tional peculiarity. Both twins are apt to 

 sicken at the same time in no less than 

 nine out of the thirty-five cases. Either 

 their illnesses, to which I refer, were non- 

 contagious, or, if contagious, the twins 

 caught them simultaneously ; they did not 

 catch them the one from the other. 



Galton found that in many cases re- 

 semblances in body and mind con- 

 tinued unaltered up to old age. not- 

 withstanding- g-reatly altered condi- 

 tions of life. He says further: 



The twins (not identical) who closely 

 resembled each other in childhood and 

 early youth, and were reared under not 

 very dissimilar conditions, either grow un- 

 like through the development of natural 

 (that is, inherited) characteristics which 

 had lain dormant at first, or else (if iden- 

 tical twins) they continue their lives keep- 

 ing time like two watches, hardly to be 

 thrown out of accord, except by some 

 physical jar." 



In the same careful, cautious man- 

 ner, Galton examined the records of a 

 larg-e number of ordinary twins who 

 were unlike from the start. It is a 

 long catalog of increasing dissimilari- 

 ties in many respects of body. mind, 

 disposition, ability, immunities and 

 susceptibilities, although the environ- 

 ment and training had been very much 

 the same throughout. 



He then concludes : 



There is no escape from the conclusion 

 that nature prevails enormously over nur- 

 ture, when the differences of nurture do 

 not exceed what is commonly to be found 

 among persons of the same rank in society 

 and in the same country. 



So far practically all the discussion 

 has centered on the question as to 

 whether or not induced, or acquired, 

 characteristics may be transmitted in 

 the heritage. An effort has been made 

 to present an unbiased surnmary of 

 the evidence both for and against the 

 idea. The only fair conclusion which 

 seems possible is that the question 

 may not at the present time be an- 

 swered positively with yes or no. As 

 indicated already, however, the alleged 

 positive evidence is not satisfactory, 

 while the facts against the idea are 

 certainly quite strong. 



Mendelian Heredity 



The sentiment of Jacob Riis. and 

 the word sentiment is here used ad- 

 visedly, that by making the conditions 

 better in which people live we are at 

 the same time making the race better, 

 certainly strikes the popular chord. 

 If there were no alternative to this 

 view that the heritage must be modified 

 by the environment before race im- 

 provement is possible, the outlook, 

 from the point of view maintained in 

 this paper, would be gloomy indeed. 

 Fortunately there are alternatives the 

 features of which have undoubtedly 

 been involved in race improvement 

 for ages, perhaps without racial con- 

 sciousness, or at least with only racial 

 subconsciousness. These methods are 

 still available, but whether for con- 

 scious application, or not. it would 

 probably be imprudent at the present 

 time to make predictions. One of 

 these alternatives that I would like to 

 place before you for examination con- 

 sists of the principles and materials 

 of Mendelian Heredity. Naturally 

 only the barest outlines of so inclusive 

 a subject may be presented, and 1 

 shall use. for the most part, some ma- 

 terials with which I am most familiar. 



A breeding investigation using or- 

 ganisms such as the grouse locusts is 

 justified and supported on the ground 

 that this, supplemented by records of 

 the breeding results in cattle, sheep, 

 and pigs of other, including commer- 



