214 THE SMALL GRAINS 



and others in Europe and recently by several investiga- 

 tors in this country. (1) Lyon (1905, pp. 49-72) found 

 that high protein percentage in wheat is correlated with 

 small kernels, having slightly lower absolute and specific 

 weight than those of lower percentage of protein. Heavier 

 kernels contain a greater weight of protein, but a smaller 

 percentage. (2) An interesting case occurs in hulless 

 oats, wherein the hulless character of kernel is always 

 associated with an extension of the spikelet axis and a 

 large number of flowers to the spikelet. The correlation 

 is really triple, as there is associated also a membranous 

 structure of the lemma. These are, in fact, the three 

 chief characters of hulless oats. A very similar correla- 

 tion occurs in Polish wheat. Such correlations, in which 

 the characters have no direct or causal relation to each 

 other, are called by Webber (1906, pp. 75-81) coherital. 1 

 (3) Myers (1912, pp. 69-72) reports an absolute relation 

 between weight of straw and weight of grain. It should 

 be remarked, however, that the proportion of grain to 

 straw in different varieties varies exceedingly. (4) In 

 connection with the discussion of the value of large or 

 heavy seed (180-183), Love (1912, pp. 109-118) reported 

 the results of investigations in wheat and oats, showing 

 that tall, heavy yielding plants produce large seed from 

 which a correlation of these characters may be inferred. 



(5) Roberts (1912, pp. 80-109) concludes that tillering is 

 highly correlated with weight of grain to the spike. 



(6) Love and Leighty (1914, p. 64) found that in oats, 

 height and number of culms and average yield of culms 

 are directly correlated. 



Numerous other examples of correlations are reported 



1 Love and Leighty (1914, p. 68) use the term stable instead, 

 in opposition to fluctuating or environmental correlations. 



