Germination of Forest Trees 78 
In the case of one and the same species large, heavy seed are better than 
light ones. The former generally possess a greater power of germination 
and the resulting seedlings show a greater power of resistance against 
injurious external influences and a more vigorous development which in 
many species is due to the greater quantity of reserve food materials 
deposited in the seed. This superiority at the first start should not be 
underestimated because it is recognizable long after the seedling stage 
has been passed. In many cases the dominant trees grow out of the seed- 
lings which had the better start. 
The relation of size and weight of seed to germination per 
cent. and later development has been worked out to a much 
greater degree of certainty in the case of agricultural and garden 
seeds than in the case of forest-tree seeds. These facts have 
already been quite firmly established in practice and already 
adopted as a criterion of seed values. There is no reason why 
weight of seed should not play as important a part in selecting 
forest tree seeds as well as agricultural and garden seeds in the 
future, as the source and germination per cent. of those seeds. 
A considerable amount of work has been done by investigators 
upon cereals, regarding the comparative value of heavy and light 
seed used in planting. Most of the work has been done with 
wheat, oats, and barley and the preponderance of evidence is in 
favor of the large seed. The hypothesis upon which this work 
has been based was the fact that, since the weight and size of the 
seed determines largely the amount of food material immediately 
available for the plantlet at the time of germination, it is reason- 
able to assume that these factors might have some influence upon 
the life of the plant and even upon the final crop. 
Iarly experiments by Hellriegel, Wollny, Marek, and others 
(28) were favorable to the view that seeds of greater size and 
weight generally give more vigorous plants than those smaller 
and lighter. Hellriegel was of the opinion that differences at 
maturity between the product of heavy and light seeds are in- 
tensified when the conditions are unfavorable. Hicks and 
Dabney (28) have made a test of the relative effects of weight 
upon vigor, using many kinds of seeds. In the case of radish, 
vetch, sweet pea, cane, Kafir corn, rye, and oats the total weight 
of the seedlings in each case favored the heavy seed. The differ- 
ences in germination per cent. of light and heavy seed was not 
