138 MISSOURI BOTANICAL GARDEN. 



NUTRITIVE 



AND ENDOSPERM. 



between the germinating 



Till 



gated that the date has become classic. Under the above 

 caption, it is my purpose, so far as possible, to complete the 

 account by detailing the corresponding relations during the 

 embryonic period. Especial interest attaches to this phase 

 because the growing embryo opposes itself to a growing endo- 

 sperm, while during germination, the latter is wholly pas- 

 sive. 25 This opposition of two growing and anatomically 

 independent bodies must result in adjustments which may be 

 mechanical merely ; or they may be chemical with resulting 

 secondary mechanical adjustments. There must also be a 

 zone where the counter-influences meet each other, which 



may be 



Periods I and II. 

 and second periods, as I have 





pointed out, the growth of the embryo is slow. A week 

 after pollination it measures about 25 microns in diameter, 

 and attains at stage III a diameter of only 60-75 microns. 

 It is evident that, in view of the loose anatomical character 

 of the endosperm, and the slow increase of the linear di- 

 mensions of the embryo, there is but little mechanical re- 

 adjustment involved. During the first period, I have found 

 no optical evidence of digestive activity peculiar to the em- 

 bryo, although, of course, this may obtain. This is ap- 



m the fact that, at 11 weeks, all the endosp 



de 



mbryo 



seems 



mbryo and endosperm 



ological unit so far as nutrition is concerned. At any rate, 

 the reactions appear to be quite the same in both, and show, 

 e. g., that tannin is abundant in them throughout the first 



25 Pond, 1906. 





