212 R. RUGGLES GATES. 



more precise significance, but particularly the ratios 5:1 and 

 15:1 in addition to 3:1 fall so closely into definite categories 

 that the probability of there all being significant is great. The 

 foregoing table contains the F2 and F3 ratios for the various 

 families. 



Considering these data as a whole, the ratios nearly all fall 

 remarkably close to whole numbers. In the first column of 

 Table II. are given the actual ratios obtained, in the second 

 column the expectation for different ratios, and in the third 

 column the conclusion as to the ratios probably represented in 

 each case. Many of the families are larger than these of Nilsson- 

 Ehle, and in general they appear to fit the various ratios more 

 closely. 



Considering first the Fo families, it will be seen that those 

 whose ratios are 3:1 or 15:1 are in perfect or almost perfect 

 accord with expectation. This being the case, it seems probable 

 that the 5:1 and 4:1 ratios obtained are significant as such, and 

 in any case they cannot be considered merely wide departures 

 from 3:1. Of the 5:1 ratios the first, second, and fourth are in 

 perfect agreement with 5:1 while the other one is very close, as 

 is also the sum of these four families (292 :54) . The significance of 

 these facts is further heightened by the fact that three of these 

 four families (the first, third and fourth) are deri^•ed from selfing 

 different flowers of the same Fi plant. This is shown in my 

 original record of these experiments, ^ and it almost forces the 

 conclusion that in this particular plant as well as others giving 

 similar ratios, R gametes were being produced with greater 

 frequency than r gametes in the ratio 5:3. There is, however, 

 another explanation which will be considered later. 



In the results of Nilsson-Ehle, on the other hand, the ratios 

 do not fall clearly into such intermediate categories but tend to 

 form a continuous series of ratios as Kajanus pointed out. Thus 

 in one series of crosses^ between black and white glumes involving 

 only monohybrid ratios, the F2 ratios in the 13 families actually 

 range from 2.2:1 (323:144) to 4.1:1 (230:56), yet the total (2468: 

 795) is fairly close to 3:1. One of these families contained 86 



■i Zeilschr.f. Abst. ». Vererb., 11, p. 236. 

 ■2 " Kreuzungsuntersuchungen," I, p. 18. 



