Periodical Literature. 425 



that actually two grades were well differentiated. This differen- 

 tiation was on the basis of weight of the individual seeds. 



A batch of pine seeds was then sent to the firm of Kayser. In 

 a few days the seed was returned very satisfactorily separated 

 into three perfectly distinct grades. The improved results had 

 been scured by slightly modifying the separator to suit the pine 

 seeds. The differences in weight between the grades was equal, as 

 is desirable but the yield of the three grades from stock seeds is 

 very unequal, as the following table shows : 



It is recommended that the first grade be used for field sowing 

 and that the use of the third grade be avoided. 



Sprouting tests after ten days and again after twenty days 

 failed to show any significant differences in the results from these 

 three grades of seed. Haack, however, has already shown that 

 grades of seed which differ markedly under field conditions may 

 be indistinguishable when sprouted under the favorable conditions 

 of the testing laboratory. 



But if we refuse to be satisfied with the mere protrusion of the 

 radicle and measure instead the length of the root five days after 

 it has burst through the seed coat we succeed in finding a signi- 

 ficant difference between grades II and III, but not between 

 grades I and II. 



The advantage of control of the number of seedlings per hectare 

 has been recognized of late years as never before, since it has been 

 learned that the production of overdense stands of seedlings is 

 not the best practice- For this purpose the use of the heaviest 

 seeds is completely justified because it increases the probability 

 that every seed sowed will produce a seedling. Lighter seeds are 

 known to produce, on the average, fewer plants per hectare, and 

 the present practice in Prussia is to increase the rate of sowing 

 to compensate under average conditions for this lower value. 

 But conditions are seldom average and favorable circumstances 

 can readily result in heavily overstocked areas by bringing forth 



