Seed Separation as Related to Germination and the Gro7vth of 



Seedlings. 



The experiments made in our laboratory for the purpose of veri- 

 fying other experiments and illustrating the value of seed separation 

 show decided differences between small, light seed and large, heavy 

 seed, both in respect to germination and to the growth of seedlings. 

 These experiments have been mainly confined to about a dozen dif- 

 ferent varieties of seeds. Shamel and Cobey' have also demon- 

 strated differences in the case of tobacco plants, and they have 

 given some striking illustrations of tobacco plants grown from heavy, 

 medium and light tobacco seed. Clark obtained many similar 

 results with other seed possessing various specific gravities. In our 

 experiments the difference between seedlings grown from large and 

 small seeds was quite marked. The results which we obtained with 

 lettuce were similar to those to be observed in any lettuce seedling 

 bed where thousands of these plants are growing. In these beds 

 may be seedlings or prickers of various sizes and degrees of devel- 

 opment which were derived from different sizes of seed. The small 

 seed in such cases produced the small seedlings and the heavy seed 

 the larger ones. These prickers have to be selected carefully and 

 the inferior ones discarded. It is much easier, however, to accom- 

 plish the separation by the use of a sieve before the seed is sown 

 than afterwards to depend upon the eye and hand. 



The results of the separation of various seeds as shown by their 

 germination and the growth of seedlings are given in the following 

 tables. The superiority of the large seed is shown in almost every 

 instance. 



2 Shamel & Cobey, Bui. 91, Bur. Plant Ind.. U. S. Dept. Agr.,. August, 1906. 



