J44 Sammelreferat. 



In another paper on a cross between nuda and sativa, Surface and Zinn 

 have made a study of the pubescence at the sides of the base of the grain. 

 This character they report to be controlled by two independent factors, since 

 they get a clear 15 : 1 ratio. They also find that in this pubescence two 

 lengths of hair are involved, the long hairs being dominant to short, and 

 independent of other characters (10). 



Base. 



The base of the wild oat (A. fatua) is expanded into a sucker-like ring 

 and is covered, both laterally and dorsally, wdth a thick growth of rather 

 stiff short hairs. The base of the cultivated oat (A. sativa) shows a small 

 notched articulation, quite different from that of the wild type, and pubes- 

 cence is entirely absent from the base of the upper grain. The lower grain 

 may in rare cases show several slight hairs, but in the ordinary cultivated 

 oat it is absent. 



In crosses between the two types, the heterozygote is intermediate in 

 the lower grain, while in the upper grain the cultivated base is completely 

 dominant. In F,, the bases on the lower grain segregate in a 1:2:1 ratio 

 and in the upper grain on a 3:1 ratio. 



Although the wild base segregates independently of colour, this is not 

 so in the case of many other characters. There are no less than seven other 

 characters which seem always to be associated with wild base. According 

 to Surface these are (1) heavj' awn on the lower grain, (2) awns on the 

 upper grain, (3) wild base on the upper grain, (4) pubescence on the pedicel 

 on the lower gjain, and (5) on the upper grain, (6) pubescence on all sides 

 of the lower grain, and (7) pubescence on the base of the upper grain. No 

 data have so far been published to show that separation ever occurs in any 

 crossing experiments involving the wild base. However, there is some in- 

 direct evidence that separation has occurred in cultivation and Surface men- 

 tions unpublished data which make him lean towards the hypothesis of close 

 linkage rather than towards that of a single gene controlling the whole 

 association (9). In this connection it should be mentioned that both in 

 Wheat and in Barley such associations of characters have been found, and 

 in barley, at any rate, there is evidence that dissociation takes place when 

 sufficiently large numbers of plants are recorded. [Unpublished data ofEngledow.] 



Spikelets. 



The cross between A. nuda and A. sativa offers the attractive possibility 

 of combining the multiflorous spikelet of nuda with the large hulled grain 

 of sativa. This prize has so far eluded the scientist; but, from time to time, 

 seed firms have put on the market new varieties, for which they have claim- 

 ed should be devided claimed increased yield on the ground that they are 



