18 Messrs. Brown and Escombe. On the Depletion of the 



When sections of the starch-bearing portions of the mature 

 endosperm are thus treated, it is seen that the nucleus is either 

 extremely deformed, or. indeed, in manv cases even completely dis- 

 integrated. That these appearances are not in any way due to the 

 treatment to which the sections have been subjected is clearly shown 

 by an examination of sections made from the endosperms of barley, 

 taken from the fields at different stages of development, when starch 

 is still being actively deposited within the cells. In the early stages 

 of development the saliva-treatment gives sections in which normal 

 and well-defined nuclei exist, but as the grain approaches maturity 

 there is a corresponding senescence of the nucleus, resulting in the 

 appearances just described. 



It is interesting to trace the progress of this nuclear senescence, 

 which first commences in the more deeply seated and older cells of 

 the endosperm, gradually extending towards the periphery as the 

 period of maturation approaches. 



Just before complete ripening, the only well-formed nuclei which can 

 be recognised are those of the last row of starch-bearing cells imme- 

 diately under the " aleurone-layer." Ultimately, unless some 

 unfavourable circumstances arise to prevent complete maturation, 

 these nuclei to a great extent share the fate of those of the more 

 deeply seated cells, but they are generally deformed to a less 

 degree. 



We shall at a future time have more to say on this question as 

 regards other seeds and its connection with the particular nature of 

 the reserve products. The point to which we now particularly wish 

 to draw attention is that the cytological observations indicate the 

 existence of a very marked difference between the nuclei of the 

 " aleurone-cells " and those of the amyliferous cells. There can be 

 no doubt about the functionating power of the former, whereas it 

 seems difficult to admit that the starch-bearing cells can exercise 

 their full powers as living units after complete maturation, although 

 the destruction of their nuclei may not preclude all possibilities in 

 this direction. 



Nothing short of actual trial, however, can determine whether the 

 starch-containing cells of the endosperm retain sufficient vitality to 

 have any action on their own cell-membrane or cell-contents, and, 

 with this object in view, we have conducted a number of experi- 

 ments on large fragments of endosperm deprived completely of their 

 adherent " aleurone-layer " after being steeped for twenty- four hours, 

 and placed under the usual favourable conditions for the rapid out- 

 ward diffusion of any products of change. For purposes of com- 

 parison we also employed other similar fragments which had been 

 treated with chloroform-water for a sufficiently long period to effec- 

 tually destroy any residual vitality, the chloroform being removed 



