144 MISSOURI BOTANICAL GARDEN*. 





Green (1899, p. 97) in 1887 studied the progress of diges- 

 tion in the germinating seedling of Livistona humilis, which 

 is quite similar structurally to the date. After two months 

 germination at which time the endosperm was about half 

 absorbed, Green found that the "inner zone" 27 of the digested 

 ion of the endosperm gave a blue reaction with iodine. 



but 



Green concluded 



that under the action of a cytatic ferment the cell wall 

 (primary membrane) was changed. This form of digestion 



mbrane 



as 



m * x x 



he was right. During the embryonic period, however, it is 

 otherwise. My observations show that soon after a stage rep- 

 resented by figures 14a, 26, when the adjustments between 



me 



chanical, a substance is secreted, presumably by the embryo, 

 which acts upon the nearest cells, attacking the primary 

 membrane and changing it into an amyloid, as I may call 

 it for the present. The reaction indicative of this conclusion 

 is to be seen clearly at a stage represented by figure 15, in 

 which a column of cells {a, in the figure) opposite the 

 apex of the embryo all show a distinct and characteristic* 

 blue coloring. The walls themselves in zone a appear wavy 

 and more or less crumpled by lateral pressure of the cells of 

 zone a', and show every appearance of undergoing some 





sort of change. The blue reaction is shown also by the walls 

 of the uncrushed cells (a, f. 15) flanking the column of 

 crushed cells (a, f. 15). This behavior in the presence of 

 iodine indicates clearly that the membranes are undergoing 

 a chemical change, hydrolytic in nature, similar to that 

 observed by Green during germination in Livistona. 



That this digestion is such in fact is shown also by the 

 behavior of the crushed cell Avails (a, f. 20) nearer the 

 embryo as compared with those in a layer further removed 

 a', f. 20). The former are directly dissolved by sulfuric 

 acid while the latter spread out and take their normal form 

 before dissolution. The exceedingly tenuous character of 



27 I understand this to mean that next the haustorium. 



