Notes. 389 
and the peripheral parts of the aleurone-grains become coloured, but 
the central parts of the grains remain colourless. 
(b) Treated on the slide with a 1 per cent, solution of caustic 
potash , the protoplasm swells up and partially emerges from those 
cells which have been cut open : the peripheral parts of the aleurone- 
grains dissolve, but the central parts of the grains remain unchanged, 
so that at this stage the cell-contents present the appearance of 
a hyaline mass in which are suspended innumerable spherules. After 
washing thoroughly with water, the spherules dissolve in 1 per cent . 
acetic acid or in picric acid. Hence they are not composed of calcic 
oxalate, or of proteids, but are probably ordinary globoids. This is 
confirmed by their dissolving in an ammoniac al mixture of ammonic 
chloride and hydrodisodic phosphate : here they are replaced by well- 
defined crystals of double phosphate of magnesium and ammonium 
(P 00 2 Mg 0 NH 4 ). This proves that the spherules contain magnesium. 
Heated dry on a coverslip, after the washing away of the caustic 
potash, the spherules turn brown but retain their shape even after 
prolonged heating — thus showing that the spherules are globoids. 
(c) Treating sections which have been freed from oil with picric 
acid , and washing well with absolute alcohol, the spherules dis- 
appear from the aleurone-grains which now remain behind as hollow 
spheres. Treating such preparations with a 1 per cent, solution of 
caustic potash , no spherules remain behind. If ammoniacal ammonic 
chloride and hydrodisodic phosphate be supplied to the sections there is 
no deposit of crystals. Hence the spherules have been dissolved by 
the picric acid, and it is they which contain the magnesium. 
(iii) To avoid any possibility of error due to the use of absolute 
alcohol, the above-described methods were applied to sections from 
which oil had not been removed and which had not been treated with 
alcohol. These observations confirmed the previous ones, though 
the presence of oil made it much more difficult to see the nature of 
the aleurone-grains. 
As will be seen in the special work described later on, the aleurone- 
grains in the cells in question sometimes contain no globoids. 
As to the nature of the proteids in the aleurone-grains, I devoted 
but scant attention to the matter. But after the employment of 
alcohol the proteids of the aleurone-grains are at any rate partially 
insoluble in water. Under the same circumstances, in Zea Mays , 
they are not dissolved by 1 per cent, caustic potash, even after 
D d 2 
