GENETIC TYPE AND THE ENDOCRINES 75 



of seven, each containing only one female puppy, while the 

 sister, 508 9 , gave a litter of eight and a litter of six with 

 only one male pup each, and a litter of seven and a litter of 

 nine with only two males each. Other litters produced by both 

 mothers were more nearly divided for males and females. 



The F 2 generation showed most instructive conditions in 

 leg length and bone type. The bottom row of plate 10 illus- 

 trates a single litter of seven F 2 adult animals. Three of 

 these, 14415 (fig. 5), 1439 c? (fig. 8), and 1445 9 (fig. 11) are 

 double short or ss for achondroplasia; three, 1440 3 (fig. 6), 

 1442 $ (fig. 7), and 144.3 $ (fig. 9) are intermediate or mixed, 

 si; and one animal, 1444 6 (fig. 10) shows very long, //, Saluki 

 legs. Tims in this litter appear the three expected kinds of 

 legs: the dominant pure short ss, mixed short si, and the 

 recessive pure long 11. But an element which was not so no- 

 ticeable among the bassethound-shepherd F L > animals, although 

 it was ] tresent, is clearly presented in these. The Saluki typed 

 bone and the bassethound typed bone tend to segregate in a 

 rather definite manner, while at the same time the achon- 

 droplasic growth occurs with both bone types. This fact in- 

 troduces a second element in the determination of leg length 

 and pattern and the degree of achondroplasic reaction, and 

 because of this second element the three animals, figures 5, 

 8 and 11 in plate 10, although diagnosed as double short, ss, 

 are not all equally short. No. 1445 9 (fig. 11) is the tallest 

 and 1439 6 {fix;. 8) the shortest of the three. These two animals 

 are better shown and less reduced in size in plate 11 (fig. 3, 

 right, and fig. 4). The shortest one, 1439 3 (fig. 4) is seen to 

 have a most pronounced achondroplasic distortion of the 

 stocky, bassethound-like front legs. The two factors, ss, for 

 short affecting this stocky bassethound bone produced a very 

 pronounced reaction. Conversely, the pure ss short condition 

 acting upon the slender Saluki typed bone in 1445 9 (right in 

 fig. 3), produced a less marked effect, and this dog shows 

 legs almost as long as the mixed si F x hybrids (figs. 1 and 2) 

 and with even slenderer bone. This animal appears to have 

 almost pure Saluki typed bone and the achondroplasic modi- 



