EMBRYO, SEED AND CAKPEL IN THE DATE. 131 



from 



part of the outer integument 

 comes insoluble; it is found t< 



be 



* « 



There is evidence that during development tannin moves 

 from the integuments and raphe into the endosperm, as well 

 as from the chalaza, where the activity is especially evident 



(f. 27a). 

 Endosperm. Stage I. A strong tannin reaction is seen 



in the embryo-sac. Just at the time of pollination the 



endosperm nucleus and its protoplasm become blackened 



by iron following copper. The same evidence is had by the 



use of ethyl nitrite, which gives a brown reaction. Alcohol 



material gives a less pronounced, but readily observable reac- 



tion. 



or a period of eight weeks, or somewhat longe] 

 m retains a syncytial character, and remains 



thin protoplasmic lining. All the material collected during 

 this period (Rhars and Deglet Noor — in alternate weeks) 

 shows that during the whole of this time, the endosperm is 

 always replete with tannin. Copper acetate and ethyl nitrite 

 material invariably show also a thick precipitation mem- 

 brane lining the endosperm utriculum, from which it must 

 be argued that the fluid within was rich in soluble tannin. 

 It is also to be inferred from the facts of distribution, that the 

 tannin is diffusible, and this is supported by a study of the 

 endosperm in a later stage. 



Stage II. From this time on the endosperm develops 

 centripetally (f. 10), but this more rapidly in the chalazal 

 cul-de-sac than at the micropylar end. During the periods 



between 



embry 



comes to lie definitely in the familiar midway position. 

 (f. 12). The filling of the utriculum occupies about four 

 weeks, in which time the seed attains a length of 9 mm. 

 with a diameter of 3 mm. (Deglet Noor). The lack of 

 any pronounced tannin reaction (more marked in the peri- 

 pheral cells than elsewhere) at this time, indicates that there 

 has been a substitution of one material for another. As a 

 matter of fact for the first time there is to be noted a general 



