.270 



First and Second Toes in Man 



Only 6 lojitings ti x ^4 and »S' x B were recorded, these produced 24 

 offspring, 15 L, 7 S, 2 A and B, or 15 Jj type and 9 of the other types. 

 Again there is dominance of the L type, but the proportion, 15 : 0, 

 indicates a very real genetic difference between this type of mating and 

 L X {A or B) in which the offspring are as 3f : 1 or 15 : 4. 



The five remaining matings between A and B types gave only (i 

 offspring, 5 L and 1 A, the L factor being preponderatingly dominant. 

 The behaviour of A and B with one another and with S and L respec- 

 tively, makes it clear that they are heterozygous types, just as the 

 matings L x L and S x S show that these are generally pure types for 

 the character under consideration. 



The net result of all these groupings is to show that the L toe-type 

 is the dominant, the dominance being, so far as yet determined, irregular. 

 The usual heteroz5'gous forms are A and B, but some L types also 

 behave as heterozygotes. That L may bo both a hetero- and a homo- 

 zygote is seen from Fig. 6, Tree G. 



FIGURE 6. 



Tn-,' a. 



(1) 1 



? = c? 



/. I n 



.1 I /. 



! I I /\ I I /\ I I I /\ ! I I ! 

 c?(J?(?99cJ(?99c?9cJ9c?c5?? 



B L .y L S L L L ,S L L L L L L L L L 



Two geuei-atiims to show the two values of L. Amongst the oftspriiig aro 

 three pairs of orchiiary twins. 



Tn-e H. 



2. 



