TRITICUM 99 



yielded 25 bushels per acre; in the full-ripe stage, 30 bushels 

 per acre, and in the dead-ripe, 28 bushels. The dead-ripe 

 stage produced the most vigorous seed, as was determined by 

 the length to which the plumule would grow. For example, 

 in the above experiment wheat collected in the dough stage 

 produced a plumule g^inches long, in the full-ripe stage 10. i 

 inches long, and in the dead-ripe stage 1 1 inches long. Similar 

 experiments with rye have shown that plants from immature 

 seeds lack vigor, and also that a large percentage fail to 

 germinate. There is some experimental evidence that by 

 continually planting immature seeds an earlier ripening strain 

 may be obtained. 



The Mature Grain. — The average weight of 100 kernels of 

 common bread wheat is about 3.866 grams. Durum wheats 

 weigh more per 100 grains. Although the results are con- 

 flicting, there are insufficient positive results to warrant the 

 belief that large plump seeds will give uniformly greater 

 yields than small seeds, especially when such seeds are secured 

 by means of the ordinary fanning mill. It is known that not 

 all the grains in a spikelet are the same size and weight — 

 the second is the heaviest, the first and third about equal in 

 weight, and the fourth and fifth, if present, are lightest of 

 all. It is obvious that all grains from a spikelet regardless 

 of their size, have the same heredity. And a light seed from 

 a spikelet usually will, under similar environmental condi- 

 tions, develop into a plant with as much vigor as one from a 

 heavy seed from the same spikelet. In the selection of seed 

 wheat, the individual plant should be the basis of selection, 

 when such method is practicable, rather than to depend 

 upon seed from the bin or sack, which is the offspring of 

 many different parent plants. 



There is a tuft of hairs, the brush (Fig. 34) at the small 

 (stigmatic) end of the grain, and at the opposite end the 



