PHYSICAL CHARACTERS IN MAN 139 



from the mother, and 25 per cent, more women 

 than men inherit asthma directly from the parents." 



It is concluded (i) that where both parents have 

 asthma or hay fever, all the children tend to show 

 the condition. (2) Where one parent has asthma 

 and one is normal (seventeen matings), all the chil- 

 dren (sixty) were normal. (3) When one parent is 

 asthmatic and one normal, but probabl}' carrying the 

 condition (simplex), then equal numbers of the off- 

 spring are affected or unaffected (sixt}^ asthmatic and 

 sixty-seven normal). (4) When both parents were 

 normal, but could be shown or must be assumed 

 to be carrying the condition (simplex), there were 

 three times as many asthmatic as normal children. 

 This is the reverse of expectation. It is partly ex- 

 plained by incomplete records of normals, and in part 

 by the addition of the non-transmitting type of 

 asthmatics. But it is at least possible that in a 

 character of this kind, in the cross DR x DR the 

 recessive character is able to express itself in some 

 instances in the heteroz3^gous condition. Whether this 

 is the case can be determined from further evidence, but 

 it appears probable that characters may depart from 

 strict recessive Mendelian behaviour in this respect. 



Reference may be made here to the studies of 

 tuberculosis by Pearson (1907) and Goring (1909). 

 They compared the correlation between parent and 

 offspring as regards the incidence of the disease with 

 that between husband and wnfe, in order to determine 

 the relative importance of inheritance and infection 

 in the development of this disease. Pearson found a 

 correlation of 0-5 between parent and offspring, which 

 is about the same as for such characters as eye colour, 

 height, etc., indicating the same tendency to in- 

 heritance. Husband and wife, on the other hand, 

 gave a correlation of 0-24, and much of this was be- 

 lieved to be due to assortative mating. Pearson's data 



