EMBRYO, SEED AND CARPEL IN THE DATE. 



159 



7. Oil. There is no oil in the carpel, integuments or raphe at any 



time. 



Oil first appears in the endosperm during the process of ingrowth 

 leading to the obliteration of the utriculum. The amount increases 

 steadily until the utriculum is obliterated, or shortly thereafter. 

 There is then a reduction in amount until the secretion of reserve 

 cellulose has advanced somewhat, at a time approximately between 

 that represented by figure 26a and that by figure 27. It then accum- 

 ulates till the resting condition is reached. During germination it is 

 digested before passing into the embryo. 



In the embryo, oil has been found soon after it appears in the 

 endosperm. There continues throughout the embryonic period a 

 digestion of oil in the endosperm, which is carried on in the same 

 manner as during germination. Its appearance in any part of the 

 embryo is correlated with the relative cessation of activity in that 



part. 



8. Digestion of the primary cell walls near the embryo occurs. This 

 begins approximately between the stages represented by figures 14a 

 and 15. The evidence for this conclusion is to be found in the change, 

 effected in the cell walls, in a column of tissue opposite the cotyle- 

 donary pole of the embryo. Here the walls react to rather strong 

 iodine (KI-I) by becoming blue. This material appears to afford but 

 a relatively small amount of food material. The same form of diges- 

 tion has been described by Green in Livistona during germination. 

 In the date, however, it ceases at the entrance of the embryo upon 

 the resting stage, or, at the latest, very soon after germination be- 

 gins. During the embryonic period therefore, the primary membranes 

 are digested, and this, as recorded by Sachs, does not occur during 

 germination. The middle lamella appears to persist. 



9. As shown by Pond, the digestive ferments are secreted by the 

 embryo entirely. It is here shown that the secretion is localized, and 

 is not equally active throughout the superficies of the embryo or 

 haustorium. But this does not wholly explain the behavior of the 

 movement of the haustorium through the endosperm. 



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