274 Prof. Karl Pearson. 



characteristic in the ancestry of either A or C, or again as to the 

 chance of the characteristic arising as a congenital sport, quite inde- 

 pendently of any heredity. It seems unlikely that the observation 

 of rare and isolated cases of asserted telegony will lead to any very 

 satisfactory conclusions, although a well-directed series of experi- 

 ments might undoubtedly do so. On the other hand, it is not impos- 

 sible than an extensive and careful system of family measurements 

 might bring to light something of the nature of a telegenic influence 

 in mankind. 



If such a telegenic influence really exists, it may be supposed to 

 act in at least two and, very possibly, more ways. 



(a) There may be in rare and isolated cases some remarkable 

 change produced in the female by mating with a particular male, or 

 some remarkable retention of the male element. 



(6) There may be a gradually increasing approximation of the 

 female to the male as cohabitation is continued, or as the female 

 bears more and more offspring to the male. 



It is extremely unlikely that any system of family measurements 

 would suffice to bring out evidence bearing on (a). On the other 

 hand, a closer correlation between younger children and the father, 

 and a lesser correlation between younger children and the mother, as 

 compared with the correlation between elder children and their 

 parents might, perhaps, indicate a steady influence like (&) at v\rork 

 in mankind. Shortly, such measurements might suffice to answer 

 the question as to whether younger children take more after their 

 father and less after their mother than elder children. Without 

 hazarding any physiological explanation as to the mode in which 

 telegonic influence can or does take place, we may still hope to get, at 

 any rate, negative evidence as to a possible steady telegonic influence 

 by an investigation of suitable family measurements. 



(2) Unfortunately, the collection of family data is by no means 

 an easy task, and to procure those head-measurements, which, I 

 think, would be most satisfactory for the problem of heredity, would 

 require a large staff of ready assistants, and could only be undertaken 

 on the necessary scale by the action of some scientific society or 

 public body. The data concerning 800 to 900 families which have been 

 recently collected for me deal only with stature, span, and arm-length, 

 which are measurable with more or less accuracy by the untrained 

 observer, and are only suitable for more or less rough appreciations of 

 hereditary influence. The numbers in each family measured were 

 strictly limited, in order to remove the influence of reproductive 

 selection from the determination of the correlation between parents 

 and children, and the result of this limitation has been that compara- 

 tively few couples of elder and younger brothers, and of elder and 

 younger sisters are available. They were, indeed, collected in the 



