I 9 2l] 



PACK—JUNIPERUS 



45 



a series of fundamental changes before germination. Of the many- 

 points of attack that are suggested by these experiments two were 

 chosen: (i) changes preparatory to germination, and (2) means 

 of shortening the after-ripening period. 



Changes preparatory to germination 



These are the changes that occur in the seeds stored at 5 C. 

 which prepare them for germination. As the embryo of the dry 

 seed is morphologically complete, increases very little in size, and 

 shows only the transformation of cell contents, these processes 

 could be spoken of as "foregermination"; but as this term has 

 not been used in this country these processes will be referred to as 

 after-ripening. The first point studied was the imbibition of 



water. 



TABLE X 



Showing percentage absorption of water 



(seeds dried at io5 c. for moisture determination) 



Table X shows that the seeds decreased slightly in weight after 

 a few days, even when submerged in water. In examining the 

 tables given by Lakon for the water absorption of seeds of Pinus, 

 it was noted that he incidentally obtained similar results. To 

 follow this more closely, seeds with coats on were placed on moist 

 filter paper at 5 C, and at times samples were selected, coats 

 removed, and the percentage of water in the seed, exclusive of 

 coat, determined. Table XI gives these results and the per- 

 centage of water in the seedlings as well. It should be noted that 

 the water content of the seed decreased gradually until germination, 

 when there appeared a very marked increase up to the time of the 

 developed seedling. This percentage of water seems to be related 

 to the change in the water absorbing power of seed contents, and 



