MOEPHOLOGY OF THE BAELEY GEAIN. 9 



smaller while still retaining their uniform shape, but by the corrosive 

 action of a powerful digestive diastase. The grains become irregu- 

 larly pitted and are rapidly absorbed. 



The cells fh^st affected are those in contact with the scutellum. 

 According to Brown and Morris the first visible change in the appear- 

 ance of the starch grains in the endosperm cells is coincident with 

 the fii'st appearance of starch in the cells of the scutellum, imme- 

 diately back of the epithelial layer. After the first layer of endo- 

 sperm cells has been broken through, the process gradually extends 

 through the remainder of the endosperm. The action takes place 

 along three lines: (1) It slowly proceeds directly into the mass of 

 the starch endosperm; (2) it moves with more rapidity through the 

 area immediately adjacent to the aleurone layer; and (3) it follows 

 along the furrow at an even greater rate. The course of attack is 

 thus directly opposite to that of the infiltration of starch. The cells 

 last to receive deposits of starch are the regions of most rapid deple- 

 tion. At the end of four or five days' slow germination, the path 

 of affected tissue appears in longitudinal section as more or less 

 of a crescent, the horns well advanced beneath the aleurone layer. 

 Indeed, the crescent is already apparent in Plate II, figure 2, where 

 germination was arrested at the end of the second day. 



As germination advances, the tissues earlier affected become almost 

 entirely liquefied and the diastatic and cytatic action proceeds to 

 the reduction of the remaining endosperm areas. The last parts 

 to yield are the dense deposits in the center of the flanks of the grain 

 and especially those farthest from the scut(>llum. The epithelial 

 layer undergoes some significant modification during this progressive 

 starch solution. As previously noted, the cells first elongate slightly 

 and certain changes take place in the protoplasm. Later there 

 occurs (and more or less rhythmically reoccurs) a deposit which 

 gathers in the outer ends of these cells. When the digestion is almost 

 complete, the (•j)ithelial cells midergo a sudden elongation, attaiuijig 

 a length almost four times that which marked their former condition. 



In the process of malting, the aleurone layer is not affected. It is 

 found intact in brewers' grains even after they have endur(Ml the 

 heating and strong diastatic action of the mash tub. In Jiornud 

 growth it is only when the plant has developed to tlic j)oint of exhaust- 

 ing the starch cudospcrni thjil this inyer begins to disijit('grat(> ajid 

 is absorfx'd by tlic plant. 



( ONVKRSION OF THE KNDOSPERM. 



Tlic iiiorphologicjil eliiiuges in, tiic cndospcrin arc, <»l' conisc, only 



the visible effects of the essential actions, which iiic cnzyninl ic 



Tlie disirilegralion of the ecll walls is a clicniical t lansrornial ion of 



cellulose to sugar and other coinpounds. TJic hreaking (1(»\\ u of file 



T.^yio'— Hull. i8.>-i5 — 2 



