on heeedity in rabbits. 297 



Table 15. 



Extracted Albinos X Hybrid Normals (F^). 



Matinys. Normal. Albino. 



E A 15 X H 12 4 3 



E H 18 X E A 14 4 2 



E H 19 X E A 14 1 4 



EH19 X EA14 2 4 



EH21 X E A38 5 2 



EH 21 X EA14 3 4 



E A 34 X E H 37 2 4 



EA 39 X EH 41 2 1 



Total 23 24 



From the above experiments with albinos of the second gene- 

 ration extracted from the normal hybrids of the first generation 

 it is clear that not only are the extracted albinos indistinguishable 

 in their albinism from the pure-bred albinos, but in their breeding 

 they behave precisely as do the pure-bred albinos, viz. : — (1) They 

 breed true with one another ; (2) they are recessive to pure 

 normals ; (3) they give mixed offspring when mated with hybrid 

 normals. These facts are all in accordance with the Mendelian 

 conception of gametic purity ; and there seems to be no doubt that, 

 notwithstanding their hybrid origin, these extracted albinos are 

 pure albinos. 



The normal individuals of the second generation, tested with 

 albinos and hybrids, proved to be of two kinds, pure and hybi'id ; 

 the former producing all normals, and the latter a mixture of 

 normals and albinos. Out of 21 individuals tested, 7 were 

 extracted from hybrids of the first generation mated back with 

 the original albinos (H X A), and these all proved to be hybrids 

 in accordance with the MeDdelian expectation. 2 individuals 

 were extracted from 2 hybrids of the first generation mated back 

 with the original normal (HxN), and these have so far proved 

 to be pure normals ; the Mendelian expectation for 2 such indi- 

 viduals is 1 pure and 1 hybrid. The remaining 13 individuals 

 were extracted from hybrids of the first generation bred together 

 (H x H), and of these 4 proved to be pure normals and 9 were 

 hybrid normals ; the Mendelian expectation for 12 such individuals 

 is 4 pure and 8 hybrids. 



The 6 pure extracted normals mated with 4 albinos and 8 hybrids 

 produced 83 young, all normals in accordance with the Mendelian 

 expectation. The individual matings were as follows : — 



