166 BIOLOGY OF DEATH 



family. We have seen that it demonstrates with the ut- 

 most clearness and certainty that there is an hereditary 

 influence between parent and offspring affecting the ex- 

 pectation of longevity of the latter. Bell's method of 

 handling the material does not provide any precise meas- 

 ure of the intensity of this hereditary influence, nor does 

 it furnish any indication of its strength in any but the 

 direct line of descent. Of course, if heredity is a factor 

 in the determination of longevity we should expect its 

 effects to be manifested as between brothers and sisters, 

 or in the avuncular relationships, and in greater or less 

 degree in all the other collateral and more remote direct 

 degrees of kinship. Happily, we have a painstaking 

 analysis, with a quantitative measure of the relative in- 

 fluence of heredity in the determination of longevity, 

 which was carried out many years before Bell's work on 

 the Hyde family, by the pioneer in this field, Prof. Karl 

 Pearson. His demonstration of the inheritance of longev- 

 ity appeared more than twenty years before that of 

 Bell. I have called attention to the latter 's work first 

 merely because of the greater simplicity and directness of 

 his demonstration. We may now turn to a consideration 

 of Pearson's more detailed results. 



PEAKSON'S WORK 



The material used by Pearson and his student, Miss 

 Beeton, who worked with him on the problem, came from 

 a number of different sources. Their first study dealt 

 with three series from which all deaths recorded as due 

 to accident were excluded. The first series included one 

 thousand cases of the ages of fathers and sons at 

 death, the latter being over 22.5 years of age, taken 



