INFLUENCE OF ORDER OF BIRTH, ETC. 307 



child that lived for 35 or more years. Now, suppose that in 1910 

 we select a group of individuals from the families of twelve in the 

 population. It is obvious that our group would contain many 

 more of the twelfth born from the old families than from the later 

 ones. It is evident from these considerations that when we sim- 

 plify the problem of handicapping the first born by considering 

 the ordinal position of the marked member within families of a 

 particular size, we do not avoid all statistical pitfalls. Our data 

 collected by the methods generally employed would be affected 

 by increase of population and decline of the birth rate, to say 

 nothing of other possible factors. 



Mention may be made of one circumstance which might make a 

 real difference between the first and subsequent members of a 

 family, and that is inherited syphilis. It is a well-known fact 

 that the early born are most seriously injured by this disease. 

 The not uncommon history of a syphilitic family is first the 

 occurrence of one or more abortions, then the birth of weakly 

 children and finally the production of children who are com- 

 paratively healthy. The inclusion of any considerable number 

 of such family histories would tend to cause the first born to 

 occupy an unenviable position. Since syphilis predisposes the 

 patient to tuberculosis there would tend to be an exaggeration 

 of the latter disease and probably also insanity and other patho- 

 logical defects among the early born. 



So far as pure heredity is concerned we should naturally 

 expect the first born to have the same endowments as the sub- 

 sequent members of the family. Primacy of birth as Auerbach 

 remarks is "Rein vererbungstechnischer Begriff." Whatever 

 effects may be due to maternal immaturity or the difficulties 

 incident upon bearing the first child are to be regarded as somatic 

 phenomena which there is no reason to believe produce any 

 inherited effect. How long it takes for initial handicaps which 

 are observed to preponderate in first born children to be out- 

 grown, or whether they are ever outgrown, we are unable to 

 decide. 



Those who occupy the position of first rank in their families 



