Febkuaey 24, 1899.] 



SCIENCE. 



285 



gamic union. It is rather a problem of 

 ■whether his fecundity lasts as long as his 

 wife's. We find definite inheritance of this 

 sterile tendencj' from father to son, although 

 for the reason just given it falls below that 

 indicated hy the law of ancestral heredity. 



Lastl}', the inheritance of fertility in the 

 woman through the male line is dealt with, 

 and it is shown that a woman's fertility is 

 as highly correlated with that of her pater- 

 nal as with that of her maternal grand- 

 mother. In other words the latent char- 

 acter, fertility in the woman, is transmitted 

 through the male line, and witli an in- 

 tensity which approximates to that required 

 by the law of ancestral heredity. Inci- 

 dentally the problem of ' heiresses ' is dealt 

 with. It is shown that in the case of wo- 

 men that are chiefly ' heiresses ' there is at 

 once a considerable drop in the correlation 

 between their fertility and that of their 

 mothers, while there is a small drop only in 

 their average fertility. In other words, an 

 ' heiress ' is not to be looked upon as com- 

 ing in general from a sterile stock, but as 

 having a mother whose fertility has a fic- 

 titious value, i. e. , the apparent fertility of 

 the recoi-d is not the potential fertility, the 

 inherited character, in the mother. In 

 other words, ' heiresses ' are not as a rule 

 due to sterile mothers, but in the bulk are 

 due to such causes as late marriages, re- 

 straint, incompatibility of husband and 

 wife, absence of sons or death of other 

 children, etc. 



7. Part III of the memoir contains the 

 results of a somewhat laborious investiga- 

 tion into the fecundity of brood-mares, 

 which has been a number of years in prog- 

 ress. Had better material been available 

 for the inheritance of fecundity we would 

 gladly have adopted it in preferance to 

 dealing with such an intricate subject as 

 the breeding of race-horses. Unfortunately, 

 the absence of place and means hindered 

 any experimental investigation on our part 



into the inheritance of fecundity in some 

 simpler type of life. Such investigation 

 ought certainly to be made by a trained 

 biologist, with the knowledge and the lab- 

 oratory at his disposal. 



After discussing at length the steps taken 

 by us to measure and tabulate the fecundity 

 of brood-mares, we deduce the following 

 conclusions : 



(i.) Fecundity in the brood-mare is in- 

 herited from dam to mare. 



(ii.) It is also inherited from grand-dam 

 to mare through the dam. 



In both cases the intensity is much less 

 than would be indicated by the law of an- 

 cestral heredity, but the divergence is not 

 such that it could not be accounted for by 

 a percentage of fictitious values such as 

 the peculiar conditions of horse-breeding 

 warrant us in considering probable. 



(iii.) The latent quality, fecundity in the 

 brood-mare, is inherited through the sire ; 

 this is shown not only by the correlation 

 between half-sisters, but by actual deter- 

 mination of the correlation between the 

 latent character in the sire and the patent 

 character in the daughter. 



(iv. ) The latent quality, fecundity in the 

 brood-mare, is inherited by tlie stallion 

 from his sire. This is shown not only by 

 the fecundity correlation between a sire's 

 daughters and his half-sisters, but also by 

 a direct detei-mination of the correlation 

 between the latent quality in the stallion 

 and in his sire. 



In both these cases of latent qualities the 

 law of inheritance approaches much more 

 closely to that required by the Galtonian 

 rule. This is probably due to the fact that 

 the determination of the correlation is 

 thrown back on the calculation of the means 

 and variabilities of arraj's, and not on the 

 direct calculation of the correlation between 

 fecundities, a large percentage of which are 

 probably fictitious (see § 5). 



8. Parts II and III accordingly force us 



