A. St Clair Caporn 235 



This gradual diminution in the number of tight paleae, and increase 

 in the number of loose, towards the tip is a tendency noticeable in 

 every heterozygous panicle. 



Colour. 



Owing to the impure condition of the Nuda parent as regards 

 colour, the plants raised from the crosses with the white husked 

 varieties, Thousand Dollar and Ligowo, were a mixture of greys and 

 whites. The presence of greys, however, demonstrated the dominance 

 of the grey colour whenever the cross grey x white actually occurred. 



In the case of Nubischer Schwarzer x Avena nuda the F^ colour 

 was a bright brown sometimes overlaid with a faint greyish flush. 

 Here the variability of the i\ may also be due to the fact — established 

 in another experiment — that the black parent is really made up of at 

 least three different kinds of blacks, represented zygotically by the 

 formulae 



BBB'B' GG 



BBB'B'gg 



BB b'b'gg 



where B and B' are factors for blackness, and G for grey colour. 



The F^ and F^ Generations. 



Paleae. 



No meticulous examination of the pales in the F^ generation was 

 made. The mixture of types looked so bewildering that there seemed 

 no alternative but to rub out the panicles and note the actual propor- 

 tion of tight and loose grains. This w^as done. 



TABLE III. 



1 Thousand Dollar <? x Avena nuda ? 213 panicles gave 64 with all grains tight 



2 Avena nuda c? x Ligowo ? 172 ,, ,, 49 ,, ,, 



3 Reciprocal Cross 133 ,, „ 31 ,, ,, 



Grand Total ... 518 „ „ 144 ,, ,, 



Here appeared to be some evidence of a 3 : 1 segregation, though 

 the approximation is rough, expectation on the ratio mentioned being 

 1 29 "5 instead of 144. When, however, it is remembered that only 

 single panicles were examined, that these were occasionally damaged 

 at the tips, or had lost a few spikelets elsewhere, and that although, 

 as was subsequently proved in the case of pure tight-grained forms, 

 at any rate, the single panicle is indicative of the whole plant about 



