2 1 8 
O'Brien . — The Proteids of Wheat . 
on staining with iodine. Even after five days in dilute potash 
the membrane persists ; it may, however, be dissolved by 
a concentrated solution. 
It is this comparatively easy solution in caustic potash (as 
well as in water and salt-solutions) which distinguishes the 
core of the aleuron-grains of Wheat (and probably of the 
Gramineae in general) from the globoids of other aleuron- 
grains, and which probably indicates the presence of some 
proteid body. 
Other alkaline solutions, e. g. sodium and ammonium car- 
bonates, give similar results ; so also does calcium hydrate if 
a concentrated solution is used. 
Acetic acid (i°/ o ) gradually dissolves the core from within, 
and finally the membrane also. 
Hydrochloric acid (whether i°/ o or io°/ o ) immediately dis- 
solves both membrane and core. 
Sulphuric acid (i°/ o or io°/J immediately dissolves the 
whole grain. The concentrated acid dissolves the core first, 
then the membrane ; though it occasionally appears to fix 
the latter, which then persists for some time. The last remnant 
of the core, too, frequently persists as a minute dark spot, 
indicating perhaps the presence of oil or a carbohydrate, or 
the fixation of the proteid constituent of the core by the strong 
acid. The simultaneous formation of monoclinic crystals 
(CaSOJ in the cells and their immediate neighbourhood 
shows the presence of calcium : this may be confirmed by 
adding to a dry section a solution of ammonium oxalate and 
chloride, in ammonia, when the aleuron-grains are seen to 
dissolve and octahedral crystals to appear, which are insoluble 
in acetic acid and are, therefore, presumably of calcium 
oxalate. Especially, when the section has been previously 
treated with absolute alcohol, the characteristic pink proteid 
reaction already mentioned may be observed with concentrated 
sulphuric acid. 
Nitric acid (concentrated) does not precipitate the proteids, 
but dissolves the grains at once, the cytoplasm a few seconds 
later. 
