642 EXPERIMENT STATION RECORD. [Vol.41 



showed that nearly all were heterozygous, giving in the F3 approximately three 

 plants not fully awned to one fully awned plant. The formula for these plants 

 would be li. A few partly awned plants of the F2 generation having a very 

 low percentage of awns were found to really belong to the awnless class. The 

 appearance of awns on these plants is thought to be due probably to a slight 

 modification of the action of the inhibitory factor, perhaps by environmental 

 Influences. The awnless F3 plants were found to consist of two genetic types : 

 Those plants which bred true, or practically so, for the awTiless condition, and 

 those which gave a segregation lilte that given by an Fi plant, the formula for 

 the first being //, and for the second li. 



Spikelets having two awns, one on each kernel, were found only on plants 

 having all the spikelets awned. The irregular occurrence of such two-awned 

 spikelets is thought to indicate that no definite genetic factor is involved, but 

 rather that it is the natural behavior of the awning factor to produce two 

 awns occasionally in the absence of the inhibitory factor. 



Environment seemed to affect the production of awns to a considerable 

 extent. While experimental evidence is wanting, general observation sug- 

 gested that an increase in the moisture content, organic matter, and nitrogen 

 of the soil tended to decrease the number of a^Tis. 



Strong and intermediate awns appeared in small numbers on a few of the Fj 

 plants and in about the same relative numbers on the Fa progeny of these 

 plants, as well as on the progeny of certain other F2 plants which bore only 

 weak awns. It is stated that such a phenomenon may be due to a reversion of a 

 complex nature. 



A strong linkage was observed between the fully awned condition and the 

 medium long hairs at the base of the grain. In 2,341 individuals there were 

 about 5 per cent of crossovers. A similar linkage existed between the fully 

 awned condition and the Burt (similar to Avcna sterilis) type of basal articu- 

 lation. Here there were practically 4.14 per cent of crossovers among 2,341 

 individuals. The uon-Burt type of basal articulation was dominant over the 

 Burt type in Fi, while the F2 gave three non-Burt plants to one Burt. 



Short basal hairs or no basal hairs were dominant over those which were 

 medium long, the F2 ratio being three of the former to one of the latter. 



Two colors were contrasted — a red or yellowish red in Burt, and the clear 

 yellow of Sixty Day, the Fi plants being intermediate for color. The colors of 

 the F2 plants were greatly influenced by external factors, and graded into one 

 another in such a manner as to render a perfect classification practically 

 impossible. Burt oats possessed a factor for red and a factor for yellow which 

 was distinct from the Sixty Day factor, and which carried no inhibitor to 

 awning. The genetic formula for Burt would be RB YY y' y', and for Sixty 

 Day rr yy Y' Y'. The F2 data on color agreed rather closely with the theory 

 as to the genetic constitutions of the two parents. The ratios in two families 

 approximated 48 reds : 15 yellows : 1 white. The Fa tests supported this theory 

 In a general way. The appearance of a few brown grains is thought to be the 

 result either of mutation or of reversion. Finally, the author states that while 

 other workers have shown that Sixty Day carries a factor inliibiting the pro- 

 duction of awns, whicli is closely linked with the factor for yellow color because 

 of the yellow in Burt, which carries no such inhibitor, the inhibitory effect of the 

 Sixty Day factor was obscured. 



Some further experiments with potatoes, J. Wrr.soN and F. J. Chittenden 

 (Jour. Roy. Hort. Sac, U (1919), pp. 8S-88, fig. i).— This describes observations 

 made at WIsley during 1918 on the efl"ect of spacing and of the use of seed of 

 diffei-ent origin on the yield of potatoes, supplementing work previously noted 

 (E. S. R., 40, p. 630). The spacing experiments included plantings made in 



