Some Sociological Considerations 

 Bearing on Infantile Mortality: 



A Study of Pedigrees by the Editor. 



There are five points of interest in Dr. Rutherfurd's 

 Pedigree of "Twins" (A). A glance down the lines of 

 generations shows at once that so far as this clanship is 

 concerned, the inherent tendenc}' to beget twins is trans- 

 mitted by the females.* It was evidently present in 

 several of the females of Generation B. For instance, 

 Nos. 5 and 9 both had twins among their own children. 

 No. 1 had only one child, and so, although the tendency' 

 to twinning may have been carried by her, there was 

 no chance of its manifesting itself. But that she did 

 probably inherit the character is shown b}^ the presence 

 of twins in her great-grandchildren, i.e., Nos. 11 and 

 12 in the E Generation. 



Coming back to No. 5 in the B Generation, we notice, 

 as alread}"- alluded to, that twins appeared among her 

 own children. There were two pairs, Nos. 18 and 19, 

 20 and 21, in the C Generation. But one of her daughters 

 (No. 22 C), not herself a member of twins, had nine 

 children, and among them a pair of twins. 



The second point of interest turns around the question : 

 Is there any evidence of the segregation of the twin- 

 producing capacity from the absence of it ? The part 

 of the Pedigree which apparently manifests the existence 

 of this segregation is with the woman No. 3, B Generation. 

 She had eight children and none of them twins. But we 

 are bound to ask ourselves : Would she have had twins 

 had her family been larger ? As Dr, Rutherfurd has 

 pointed out, there is an apparent tendency shown 



* In several others of Dr. Rutherfurd's Pedigrees, the twin-producing 

 quality is sometimes transmitted by the male. (See Pedigree B. 

 No. 4. B Generation. ) 



