j 2 Richard H. Boerkcr 



for Pinus pondcrosa. In the case of this species the difference 

 was often as much as ioo per cent. ; usually the difference in other 

 species did not exceed 50 per cent. Schotte (23), of the Swedish 

 Forest Experiment Station, has shown that the size of the seed 

 and the size of the cones decrease with increasing age of the tree 

 in the case of Scotch pine. The work (24) done on seeds by 

 certain forest experiment stations in Europe in 1907 with spruce 

 showed that seeds from large cones germinate earlier than those 

 from small cones ; that the largest cones produce the largest and 

 heaviest seeds and hence the largest plants ; and that the effect of 

 the size of seed upon the life of the plant has been noticed only 

 in the first two years of its growth. 



In Busse's (25) experiments pine seeds were graded by means 

 of a Kayser centrifuge into three grades according to weight. 

 The heaviest seed made up 68 per cent, of the stock seed, the 

 medium weight seed 27 per cent, and the light seed 5 per cent. 

 He recommended the first grade for field sowing but said that the 

 third grade should not be used. Sprout tests did not show any 

 differences in germination results. Centgraf (26) examined 247 

 tests of pine seed as to the relation of the weight of 1,000 grains 

 to their germination. He failed to find a relation between weight 

 and germinative energy or germination per cent. In fact he 

 found that the heavier seed averaged a smaller germination per 

 cent, than the light ones. He concluded that the slower germina- 

 tion of big seed is probably due to a thicker seed coat of the 

 heavier seed which determines in part its weight and which takes 

 up water more slowly than thin coats of light seed. Some of 

 these results do not agree with the many experiments made by 

 foresters in Europe. These tests being made for commercial 

 purposes cannot therefore be taken as conclusive. 



While the size and weight of seed has been recognized as a 

 factor in germination it also has been recognized as a factor in 

 the early development of the seedling as has been indicated in a 

 few instances above. One finds statements in regard to this rela- 

 tion quite common in silvicultural works but very little material 

 to substantiate these opinions. The view held by many writers is 

 summarized very well by Schlich in his Manual of Forestry 

 (27) : 



