No. 572] 



NOTES AND LITERATURE 



511 



on Gregory's view be 1— — : 2 — — , on the other view 1— — : 4- ■-. 

 Tests of twenty-one ~F t thrums, by mating them to themselves 

 and also to recessives, showed that there was only one which was 

 certainly — — and 15 which must have been — -. (A few gave 

 numbers too small to be significant, and one or two were of doubt- 

 ful com position.) This result is within the limits of probable error 

 on the 4 : 1, but hardly on the 2:1 expectation. The one P, 

 thrum plant which was of composition — — gave, on back- 

 crossing, 67 thrums : 18 pins, a ratio of 3.7 : 1, to correspond with 

 Gregory's 3:1 or my 5:1 expectation. On inbreeding it gave 

 44 thrums: 2 pins, a ratio of 22: 1, to correspond with Gregory's 

 15 : 1 or my 35 : 1 expectation. The other F x thrums, being of 

 composition -— (aside from the few doubtful ones), gave, on 

 the average, 1 thrum : 1 pin on back-crossing, and 3 thrums : 1 pin 

 on inbreeding ; these results would be expected on either view. 



Crosses were also made involving the character green versus 

 red stigma (green being dominant). Here the — — forms, on 

 back-crossing, gave a total of 114 green : 30 red (3.8: 1 instead of 

 3:1 or 5:1), and on inbreeding they gave 75 green: 2 red 

 (37.5:1 instead of 15:1, as on Gregory's expectation, or 35:1, 

 on my own). 



It will be seen that the numbers in the above crosses are too 

 small to be very significant, individually, for a settlement of the 

 question at issue, but if summed up they become more decisive. 

 Thus, a summary of the offspring of all back-crosses of the 

 ^"^form to the recessive gives 242 dominants (A): 54 reces- 

 sives (a), or 4.5:1, as compared with the 3:1 expectation of 

 Gregory and the 5:1 of the view advocated in this paper. 

 Where the dominants among these offspring were tested they 

 were found to consist of 1- — and 15— — , as compared with the 

 1 : 2 expectation of Gregory, and ours of 1 : 4. Finally, a sum- 

 mary of the cases where - —forms were inbred shows that 119 

 dominants: 4 recessives resulted, a ratio of 30:1 where Greg- 



