108 



Shull 



Table HI (continued). 



Fed. No. 

 of P, 



Ped. No. 

 of Pi 



Number of 

 bursa-pasloris 



Number of 

 Hecgcri 



Ratio 



Peitentagu 

 dominants 



11489 

 11492 

 11494 



1 149fi 



23-0 : 1 



21-5 : 1 

 U-5: 1 



95-83 

 95-56 

 92-01 

 9(i-52 



Total 



E X p e r ted 



■943 

 921 



,V_>S 



l.->-7 : 1 

 15-0:1 



94-01 

 93-75 



Total 



K X p e (■ t e d 



2733 

 •2C9-i 



8.i0 

 897 



3-19: 1 

 3-00:1 



76-15 



r5-oo 



The three expected g-roups appear among: the 77 families in this 

 table with great clearness, there being 39 families in the first or homo- 

 zygous group, 26 in the 15 : 1 group, and 12 in the 3 : 1 group. The 

 expected grouping for 75 families (the nearest multiple of 15) forms the 

 series, 35 : 20 : 20. The deficiency in the third groui) and the corre- 

 sponding excess in the other two groups may be significant of nothing 

 but the chance variation usually found when we deal with rclativcdy 

 small numbers, though it will be noticed that the third or 3 : 1 group 

 is numerically smaller than the; second or 15 : 1 group in all of tlic 

 three generations, Fa, Fi and Fs, included in Tables II and III. if 

 these generations are thrown together to make a grand total, the series 

 is 46 : 32 : 17, as compared with the nearest expected series 44 : 25 : 25. 



It is seen therefoi-e that the F4 and F5 families derived from the 

 15 : 1 group of the preceding generation, present a complete repetition 

 of the conditions in the Fa, adding to the evidence for duplicate deter- 

 miners nothing new in kind but only in quantity. A new kind of 



