Correlation and Application of Statistics to Problems of Heredity 105 



It is fairly clear that if the General Registry were indexed in this way, or 

 even special registries like those of the Society of Friends, pedigree making 

 would be easy work. The Family Group system becomes somewhat more 

 cumbersome in the case of rapidly breeding mammals, for example, dogs. In 

 this case it is needful to replace the family group by the dam, sire and single 

 litter, even if the mating be repeated, as the material becomes too unwieldy. 

 For very small mammals — guinea-pigs, rats or mice — where names are not 

 given, it is the index number of the individual which needs careful thought, 

 especially if it is desired to provide in that index number some indication of 

 the generation to which an individual belongs. A small letter may be given 

 to each individual in the litter attached to the family group index number, 

 and F s may be added to denote the sth generation from foundation stock, but 

 it is difficult if, say, an F 2 sire has been mated with an F 3 dam to indicate 

 this relation briefly. The difficulty is greater when such a mating is some 

 distance back in the ancestry. If such matings have occurred in considerable 

 numbers the use of generation marks in the index number of animals becomes 

 a doubtful blessing, and we may well fall back on Galton's Family Group 

 numbers plus a small letter. 



Nomenclature of Kinship. Galton, still thinking over various methods 

 of expressing kinship, turned from the numerical expression of it to seek a 

 brief nomenclature, and published in Nature, January 28, 1904 (Vol. lxix, 

 pp. 294-5) a paper entitled: "Nomenclature and Tables of Kinship." In this 

 he endeavours to give a self-explanatory, brief and euphonious name to each 

 grade of kinship, which he had in earlier papers provided with an appropriate 

 literal or numerical symbol (see our Vol. n, pp. 354-5, and the present volume, 

 pp. 44-5). He does it in the form of a schedule, here reproduced (see 

 p. 106), for recording in all his known relatives some character X known to 

 exist in A.B. This schedule is practically what he used in the same year to 

 obtain the distribution of successes in the kinsfolk of Fellows of the Royal 

 Society, a topic to which we shall return shortly. The schedule is republished 

 here because it may form a starting point for those desirous of making 

 similar inquiries. One of the most important points in it is the insistence 

 (by the presence of a separate column) on the importance of enumerating 

 the total number of relations of each class. Even up to the present year I 

 have seen disease schedules drafted in which the question is asked : How 

 many brothers (sisters, cousins, uncles, aunts, etc.) have been subject to the 

 disease? without the slightest consciousness that such information is idle 

 unless accompanied by the statement of the total number of relatives, 

 affected and not affected, in each class. 



There is only one way and that a rather incomplete one in which such 

 imperfect data can be somewhat inadequately utilised. That is by ascertain- 

 ing the average number of relatives of each class in the population at large. 

 Galton often pressed the present writer for data on this point, but there arose 

 considerable difficulties in the way of obtaining them, perhaps the chief of which 

 were the secular changes in the size of families and the infant death-rate*. 



* There are also difficulties with regard to the " weighting " of the large families both in the 

 collecting of the data, and in the actual use of them when obtained. 



pqiii 14 



