66 H. H. Lo-\t: and C. E. Leighty 



statistical method of analysis in dealing with such problems. He suggests 

 the importance of a closer analysis of our plants in order to determine 

 some of the fundamental truths that may serve as a basis for improvement. 

 The results, especially with respect to oats, reported in this paper, cast 

 some doubt on the wdsdom of planting only the heaviest seed. The 

 data as reported by Waldron show that the heaviest seed come from the 

 smaller rather than from the larger plants. This immediately raises the 

 question as to whether one can reasonably expect gains from the largest 

 seed. 



Waldron arranged his data ia correlation tables, and determined the 

 correlation between the following characters: average weight of seed 

 and number of grains; average weight of seed and length of head; average 

 weight of seed and length of culm. The calculations showed a negative 

 correlation of — 0.595 ±0.013 between average weight of seed and num- 

 ber of grains; w^hile for average weight of seed and length of head, and 

 average weight of seed and length of culm, correlation coefficients of 

 —0.511 ±0.015 and — 0.404±0.017, respectively, were fomid. The 

 constants show that the larger kernels are borne by short plants having 

 short heads and producing only a small number of kernels per head: or, 

 in other words, the smallest plants are the ones that produce the heaviest 

 seed. From these data, then, it seems possible that in sowing the heaviest 

 seed one is not using seed from the best-yielding plants. 



Some results presented m this paper are of interest in this connection. 

 These studies have to do with the relation between tall plants and average 

 weight of seed; and heavy-yielding plants and average weight of seed. 

 If there is a tendency for certain plants to produce large seed and at the 

 same tune be taller or higher-yielding than the average plants of a popula- 

 tion, then when heavy seed is selected one would at the same time be 

 selecting tall, high-;^delding plants. If, on the other hand, there is no 

 correlation between average weight of seed and height or yield, so that 

 the large seeds are borne in equal amounts by tall and short plants and by 

 heavy- and light-yielding plants, then when heavy seed is selected one is 

 at the same time selecting mediocre plants or those tending to represent 

 the average of the race. Under this condition one would not expect 

 much increase in yield from large seed, while, if the other condition 

 mentioned above holds, it would be natural to expect increase in yield 

 from large seed. 



