SEED SEPARATION. 57 



and dry tobacco seed will retain its vitality when kept dry for ten 

 years, or, as has been observed in several cases, a much longer time. 



The seeds saved in accordance with the methods here outlined are 

 larger, heavier, and of higher vitality than those saved in the ordi- 

 nary way. Self-fertilized seeds are free from the introduction of 

 hereditary tendencies from surrounding plants, and the characters 

 of a single plant are transmitted to the progeny with almost as 

 great uniformity as in the case of vegetative reproduction or propa- 

 gation from cuttings. 



This method of saving seed requires very little more time than 

 the old method, and at the same time gives the grower an opportunity 

 to study the types of tobacco in the field by coming in closer contact 

 with the seed plants themselves. He will of necessity make closer 

 observations as to the points of perfection or imperfection in indi- 

 vidual plants, and by protecting the flowers from cross-pollination it 

 is entirely possible for him to produce a pure and uniform strain of 

 tobacco after selection for two or three years, to improve his tobacco 

 in every way, and to weed out the undesirable and unprofitable 

 types which occur so frequently in the general tobacco field. 



SEED SEPARATION. 



The special value of large, heavy seed in the production of general 

 farm crops has long been established. Careful farmers and seed 

 growers have used various methods for selecting this grade of seed 

 for planting. Experiments with light and heavy seed in this and 

 other countries have demonstrated clearly and conclusively that larger 

 yields are obtained from heavy, plump grains than from small, light 

 seed. Live-stock breeders do not breed from weak or poorly devel- 

 oped parents, and it is just as important that plants be bred from 

 heavy seed with strong parentage as to use the best animals in the 

 production of improved breeds of live stock. 



The writers have found this principle to be strikingly emphasized 

 in the production of tobacco from different grades of seed. The 

 plants from large, heavy seed not only grow more vigorously, but 

 have greater resistance to certain bacterial and fungous diseases 

 and show greater uniformity in the field and warehouse than plants 

 produced from inferior seed. Thus it can be seen that the specific 

 gravity of individual seeds has a very important bearing on some of 

 the main factors in the production of profitable crops of tobacco. 

 The reason for this is very evident when we consider the fact that the 

 heavy seeds contain a larger supply of food for the development of 

 young plants than the light seeds. It is not always true that the 

 heavy seeds germinate first, or that the plantlets from such seeds make 

 the most rapid growth in early stages of development, but they always 



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