Variation and Correlation of Oats — Part I 63 



between the same characters in different years, while only one is higher 

 than all others, and five are intermediate. This condition in 1910 seems 

 to be due to the influence of undetermined environmental conditions 

 on the development of the plants and their seeds. As stated earlier in 

 this paper, this crop was grown on a different, less fertile, soil than were 

 the crops for the other years. This, together with the climatic conditions 

 of 1910, no doubt had the most to do with affecting the correlation 

 coefficients. 



By comparing the coefficients of correlation, however, for the years 

 1908 and 1910, it is seen that those for 1908 are never much lower, but 

 frequently are considerably higher, than those for 1910. The coefficients 

 for 1908 are generally high in comparison with those of all the other years. 

 Those for 1910, on the other hand, were low in comparison, as stated above. 

 It seems, therefore, that in both 1908 and 1910 there were conditions 

 operating which prevented maximum vegetative development and reduced 

 the yield, in the manner stated above; but that these conditions had a 

 different effect on the correlations, increasing, or failing to reduce markedly, 

 those for 1908, and generally decreasing those for 1910. Such results 

 would be expected if in 1908 the plants were grown on poor soil or were 

 crowded but were subject to good weather conditions, and if in 1910 the 

 plants were grown on more fertile soil or in less crowded conditions but 

 at a critical time in the development of the kernels adverse weather 

 conditions prevailed. The former premise would be in agreement with 

 the results of Myers (1912), who found, when working with wheat, that 

 correlations are higher in plants grown on poorer soil, weather conditions 

 being the same. It has been shown above that the culms used in 1908 

 were from plants grown in drill rows, thus agreeing ^vith the supposed 

 conditions. In 1910 also, as shown above, the plants were given more 

 room than in 1908, but the same room as in other years, while the weather 

 conditions were not favorable. 



discussion of results 

 The means indicate that the growing conditions were not so favorable 

 for the 1910 crop as for those of 1909 and 1912, and resulted in smaller 

 plants and a reduced total yield of grain; but that these smaller plants 

 produced a larger number of spikelets (compared with 1909 only) and 

 larger kernels. The plants of the 1908 crop were grown in drill rows, in 



