THE AMERICAN NATURALIST [Vol. LII 



that have already been collected show also that the strong 

 awn is inherited in the same manner. These data (Tables 

 I and IV) give 203 fully awned : 525 partially awned or 

 awnless, giving 2.92 : 1.12 per 4. We would expect on a 

 1 : 3 basis 182 : 546. The action of the yellow factor is to 

 reduce the amount of awns on the yellow glumed oats. 



It was stated earlier that there was apparently a 

 pubescence factor linked with the black and also another 

 pubescence factor which was not linked with any color. 

 If this were true and there was no inhibitory effect pro- 

 duced by the yellow oats we w^ould expect to obtain 15 

 pubescent to 1 non-pubescent form in the second gen- 

 eration. It may be well to state here that it has been 

 found by experiment that the wild form used in this cross 

 was of such a type that it had two factors for pubescence. 

 We have also found another form which has only one 

 factor for pubescence. When this form is crossed with 

 a white oat, all of the non-blacks are smooth, showing 

 that this form has the pubescence factor which is linked 

 with the black while the forms having the two factors for 

 pubescence give both pubescent and smooth non-blacks. 

 This is well brought out by the data presented in Table 

 VIII. Here the same white sort, Tartar King, was 

 crossed with tw^o forms of Avena fatua. 



This table is made up of data of the second generation. 

 It is possible that later experimentation may change the 

 relationship of the colors particularly so far as the grays 

 and whites are concerned. In these tables all those not 

 showing blacks and grays are classed as yellows and 

 whites. The further study of these has not proceeded 

 far enough to determine just the relation here. It seems, 

 without doubt, that we have two types of fatua, one giv- 

 ing the 15 : 1 ratio (Series 351al) and one the 3 : 1 (Series 

 351bl). Again in the 3 : 1 distribution all the non-blacks 

 are smooth. 



It will be of interest here also to state when the type 

 having one factor for pubescence was crossed with the 

 Sixty Day type similar to the one used in Series 687 that 

 all of the non-blacks, both grays and yellows, were 



