SKELETAL DIMENSIONS 



43 



The measurements made upon the 2 tliree-ciuarter-blood lops (.^492 

 and 9 504) indicate that in their production, as in that of half-loj^s, the 

 inheritance of skeletal dimensions is blending. 



It would be premature to conclude that such is the case in all mammals. 

 Farrabee (:o5) has shown that in man hypoph) langia (2-jointcd fingers and 

 toes) is associated with an abnormal shortness of the arms, legs, and trunk. 

 It would seem that all the skeletal parts are abnormally shortened. In- 

 heritance in this case is clearly not blending, but alternative. Some dis- 

 continuous alteration has evidently occurred in the growth-character of 

 cells that form the skeleton, just as in the activities of the follicle cells in 

 long-haired mammals (see Castle and Forbes, : 06). It would be of inter- 

 est to know whether such is the case also in bantam fowls and Shetland 

 ponies. 



Table 30. — Bone measurements 0/ rabbits. 



Measurement. 



1. Total length of skull . . 



2. Length, incisors to pal- 



ate inclusive 



3. Length, occipital to 



palate inclusive 



4. Width, anterior to orbit. 



5. Width, posterior to orbit 



6. Width, at auditory bullae 



7. Length jugal arch . . . . 



8. Length lower jaw 



9. Length femur 



10. Length tibia 



11. Length humerus 



12. Length ulna 



13. Length radius 



14. Length innominate . . . 



Ratio: 



4 to I 



5 to I 



1 1 to I 



13 to I 



II to 14 



Old 

 d'lop. 



mm. 

 103-7 



48.0 



67.4 



46.3 

 27.4 



364 



45-9 



0.446 

 .264 



Half- 

 blood 

 lop 

 9178. 



mm, 



104.5 



48.4 



66.5 



45-4 

 27.1 



370 



87.6 

 99.0 



79.6 

 90.2 



75-9 

 100 



0.43.S 

 .259 

 .761 

 .726 

 .796 



Expected Three- 

 mean of quarter- 

 ed 1 79 ! Wood 

 and lop 



(^178. d'49«- 



mm. 

 106.0 



49.1 



68.3 

 46.6 

 26.7 

 38.1 



0.440 

 .252 



mm. 

 107-5 

 49.0 



68.6 

 47-4 

 37-5 

 39-6 

 46.0 

 86.4 



100. 



1 19.6 

 78.9 

 91.8 

 76.7 

 97-4 



0.441 

 .248 

 •734 

 -713 

 .810 



Mean of Three- 

 old 9 lop quarter- 



(table 



29) and 



9178. 



mm. 



87.9 

 97-4 



78.4 

 893 



74-9 

 loi.s 



blood 



lop 



9304- 



0.772 



84.0 



95-7 

 109.0 



75-5 

 88.0 



73-5 

 97-3 



Half- 

 blood 

 lop 

 9167. 



0-775 



98.5 



45-3 



63.4 

 43-4 

 25.1 



35-9 

 4«-7 



89.1 

 105. 1 

 72.6 

 81.7 

 68.0 

 90s 



0.443 



•737 

 .690 



.80a 



Aside, however, from such unusual cases, it seems probable that skel- 

 etal dimensions, and so proportions of skeletal parts, behave in general 

 as blending characters. The linear dimensions of the skeletal parts of 

 an individual approximate closely the mid-parental dimensions. 



Volume and weight magnitudes, however, follow a dilTerent law, whicli 

 has not yet been clearly made out. It is jdain (hat they are less than the 

 mid-parental magnitude. (See Part II.) 



