K. J'kakso.n AM) A. Lkk 



387 



org.inic currelatioiis aiul dircct herwiity coefficient.s nvr kiiowii the cross heredity 

 coefficients iiiay hr fouiul vci'y closely Iroiii foniiulii (vü). If tlio organic corrc- 

 latioiis arc knowii, hui im licrcdily uoefficionts at. all, Ihm l.lic diruct hercdity 

 cocrticient« may approxiiiiately be takeii a.s e(|iial to ■"> and llu; cross heredity 

 cocfficietits approxiniat'cly toiind f'nmi thc organic corrclatimis hy forniida (viii). 



(ix) Direct Frateriial liescmblance. 



I iiow (iiru to the obsurvcd dcgree of rosomblaiico betvvoen brothors and sisters 

 for tlie tiirce characters we have nioasured in onr Family llucorils. We have the 



i'ollciwing results : 



TABLE IX. 



Correliifioii Cuefficieiits für Direct Fnitermil Heivdit;/. 



Now tliere are certain differences in the eutries in this Table, thii.s resemblance 

 in siblings seenis gi^eater for stature and span, than for forearm or eye-colour, and 

 agaiu the resemblance of brother and sister seems ou the average slightly smaller 

 than the resemblance between siblings of the same sex. There are also certain 

 irregnlarities, which I have no means of accounting for, and which seem larger 

 than can be explained by random samplingf. Still there cannot be the least doubt 

 from the above table that '5 measures very closely the average degree of hereditary 

 resemblance in human siblings, and that the correlation Clusters closely round this 

 value. As in the case of parental heredity we see a most marked increaso in 

 the intensity of hereditary resemblance when we compare our results vvith those 

 obtained for stature some years ago|. If we compare our Family Records with 

 the School Records, of which I only eite at present the residts for brother.s, we 



* Francis Galton's eye-colour rucord rcdiiced for niy paper on Heredity in Jlan in l'liil. Tnins. 

 Vol. 1<.)5, A, p. 106. 



+ The material, a» the reader will see by Consulting the actual tablcs, is far less. 



J Phil. Trans. Vol. 187, A, p. 281. It was the diliiculties associated with the data used in 189.5 (see 

 especially pp. 283 — 5 of above memoir) that led to tlie collection of heredity data which has been in 

 progress since 1894. 



