70 Richard H. Boerker 



plant has to go deep for its moisture. In the cases of Robinia 

 and Qucrcus the greatest length of laterals and the greatest 

 length of the tap root was found in the sand or gravel, again 

 bearing out the fact that sands and gravels are poor soils for 

 retaining moisture. 



THE RELATION OF SIZE AND WEIGHT OF SEED TO GERMINATION PER 

 CENT. AND EARLY DEVELOPMENT 



During the process of counting between 100,000 and 125,000 

 seeds of various kinds for these experiments the fact that seeds 

 of the same species varied considerably in size came to the 

 author's notice very forcibly. In his experience in the woods as 

 well as in seed extracting it was often noted that many factors 

 may affect the size of seeds. In general, it may be said that the 

 size of the seeds of any one species depends upon one or more of 

 the following factors: 



1. The size of the cone. 



2. The position of the seed in the cone. 



3. The development of the cone. 



4. The age of the tree. 



5. The physiological condition of the tree. 



6. The site upon which the tree grew. 



7. The climatic variety of the species. 



It is an old experience that large cones produce large seeds 

 and small cones small seeds. The seeds at the extreme base and 

 the extreme apex of the cone are very often very much smaller 

 than in other parts of the cone. External conditions such as 

 temperature and moisture, may affect in no small degree the seed 

 while it is maturing, thus retarding its morphological develop- 

 ment. It has been observed that middle-aged trees produce the 

 largest cones and the largest seeds, while very young or very old 

 trees usually produce small cones and small seeds. The physio- 

 logical condition of the tree may affect the size of the seed. 

 Since seed crops are dependent upon the accumulated food in the 

 tree, it is reasonable to suppose that a paucity of such food ma- 



