EMBRYO, SEED AND CARPEL IN THE DATE. 121 



deep, roughly speaking, in Rhars and Deglet Noor, the num- 

 ber of the cells depending on the size of the elements as well 

 as upon the number which may be counted in radial direc- 

 tion. Tannin similar to that in these cells occurs also in the 

 integuments of the seed, and in the mass of tissue, partly of 

 integumental, of chalazal and of funicular origin, which fills 

 the deep prominent groove characteristic of the date seed. 



Origin of the layer of tannin idioplasts. This layer makes 

 its appearance at a very early stage of development, some 

 time before pollination. For the present purpose it is suffi- 

 cient to sustain my contention to show its condition prior 

 to pollination and its development thereafter. Both fresh 

 and preserved materials including nitrous ether preparations, 



were studied. 



At this time the layer in question is continuous from the 

 base of the carpel, upwards, overarching the ovule. At the 

 base the component elements are nearly or quite spherical, 



about 



Toward the base of the 



style, where the elements are the largest, they reach a size 

 of 45-60 microns. The arch is interrupted at the apex by 

 the stylar canal and its immediately surrounding tissues, and 

 here also the thickness of the layer of four to six cells is the 

 greatest. Toward the base of the carpel, it dwindles to the 

 width of a single cell. The layer is homologous with the 

 similar tissues in the bracts surrounding the three pistils, 

 and appears the same physiologically. Precisely the same 

 condition is found in Chamaerops humilis. Tracing them 

 through the succeeding stages of development, there is no 

 change in the constituent elements, except an increase in 

 the amount of their tannin content. Other cells are added to 

 the tissue, being intercalated between those already present, 



or in a radial direction. 



The contents of the cells either lie in a layer about the 

 wall, or partially fill the lumen, and are highly vacuolated, 14 

 this, as we shall presently see, in contrast to the 

 later on. Tn material which has not been prepared with a 



same 



14 Due perhaps to the liberation of gas during the reaction. 



