EMBRYO, SEED AND CARPEL IN THE DATE. 109 



At this moment, namely at pollination, or very soon after, 

 the antipodal end of the embryo-sac shows a remarkable 

 amount of activity. This is seen especially in the very irreg- 

 ular and rapid backward extension of the endosnerm. nre- 



erm 



antipodal portion of the embryo-sac in its original position 

 (f. 3, 5). There is formed in this way a curious several- 

 armed chalazal extension which, in view of the digestion 

 of the tissues in its path 4 must be regarded as a haustorium. 

 Its function is the same, I believe, as that of analogous 

 haustorial structures formed by the endosperm in Plant ago/ 

 in w T hich, how T ever, thev are more highlv specialized in form. 



d 



as 



position and volume in the ripened seed. 6 The observed 

 phenomena relating to this activity are recorded beyond. 

 At this point it is sufficient to say that, in a week after 

 pollination, the amount of development is quite marked, 

 there being several cul-de-sacs penetrating deeply into a 

 tissue heavily loaded with tannin. At the same time there 

 is evident the beginning of that torsion which ends finally 

 in the complete displacement of the embryo (f. 5). 



Stage II. Close of the First Period. 



Carpel. The epidermis is strongly cutinized. The hypo- 

 dermal parenchyma cells are still cubical or rounded, but 

 show the accumulation of tannin. The layer of stone-cells 

 is completely developed, as also the tannin-idioplast layer. 

 Tannin-idioplasts occur also throughout the mesocarp in the 

 sutural sector (f. A, 7, 11), and in all parts of the basal 

 region. They are especially numerous near the funicle. 

 Morphologically, this is placental tissue, and is constantly 



4 At first similar in appearance to the irregular cavity formed in the 

 pine nucellus by the growing pollen tubes. 



5 Balicka-Ivanovska, 1899. 



6 It is evident that the chalaza in the mature date seed is not prim- 

 ary. Its developmental continuity, however, is clear and so we may 

 properly call it the chalaza. 



