No. 624] INHERITANCE OF HULL-LESSNESS 31 



grouped around the middle classes. This is especially 

 true with regard to the fourth generation, especially 

 when the size of the classes is doubled. 



The results of the different series are rather conflicting 

 and it does not seem possible at present to explain all of 

 them on a simple multiple factor hypothesis. It seems 

 quite possible to explain series 382 on this basis (except 

 the first generation) but the other types do not at present 

 seem capable of such an explanation. 



The distribution in Table II, which is the third gen- 

 eration of a cross between Danish Island and Hull-less, 

 is skewed much the same as for the third generation of 

 series 202. No doubt for these series there is some dis- 

 turbing factor which causes such distributions and more 

 data will be needed before a suitable explanation can be 

 found to fit all of these cases. It may be that, since in 

 crosses between two hulled sorts we have found some 

 hull-less spikelets, we have combinations such that there 

 is a tendency to produce an excess of hull-less kernels. 

 This would influence the type of distribution consid- 

 erably. 



At first one might assume that those individuals nearer 

 the lower part of the distribution were like the types, 

 however, from all the plants tested where the percentage 

 of hulled kernels has been low the frequency distribution 

 of the percentage of hulled kernels from the heterozygous 

 plants has been low in general and has not ranged from 

 very low to very high, as would be the case with seed from 

 Fi plants. These facts would help support the statement 

 just made, which is to the effect that it is possible cer- 

 tain crosses tend to produce an excess of hull-less kernels. 



Summary 



From the results presented it is evident that hull-less- 

 ness exhibits a simple Mendelian ratio of 1 hulled, 2 in- 

 termediate, 1 hull-less. 



The intermediates show all gradations of huU-lessness 

 from those nearly hulled to those nearly hull-less. 



