54 
MORPHOLOGY OF THE CELL. 
of the latter may be very small. Thus even in the castor-oil-plant and brazil-nut, 
where the matrix appears to consist entirely of oily matter, the albuminous constituent 
is quite discernible, as is shown in Fig. 48, D ; Pfeffer succeeded most readily 
by extracting with an alcoholic solution of corrosive sublimate, and then colouring 
with anilin-blue dissolved in water. The matrix may be considered as the proto- 
plasm-mass of the cell, in which the water is replaced on drying by oil. But in 
addition it contains not only insoluble proteids, but other substances soluble in 
water rendered alkaline by potash. This composition of the matrix, together with 
the solubility of the amorphous mass of the aleurone-grains in water, are the cause 
of the complete loss of form which the cell-contents of oily seeds immediately 
undergo in water, as shown in sections under the microscope. In order to recognise 
their structure it is necessary to place fresh sections in undiluted glycerin, alcohoHc 
solution of corrosive sublimate, oil, or concentrated sulphuric acid. 
The oily matter may also separate from the matrix in crystals, as Pfeffer has 
observed in the brazil-nut, Elaeis guineensis, and the nutmeg. 
To the above may be added, from Pfeffer's communication, some explanations con- 
cerning the more difficult points. 
(a) The substance of the aleurone-grains always consists, to by far the greater extent, 
of proteids, with which very small quantities of other vegetable substances are usually 
or always mixed which are difficult of detection. All aleurone-grains are absolutely 
insoluble in alcohol, ether, benzol, or chloroform^; these reagents would dissolve oil 
(alcohol dissolves also glucose), if it were present, and would consequently alter the 
appearance of the grain. Some are insoluble in water {e.g. those of Cynoglossum officinale) ; 
those soluble in water ^ yield with corrosive sublimate in absolute alcohol a mercury- 
compound insoluble in water. Gum, pectinaceous substances, cane-sugar, and dextrin 
do not, under this treatment, yield an insoluble compound. Of all widely distributed 
vegetable substances, only proteids behave in this manner towards corrosive sublimate. 
Boiling the mercury-compound with water reproduces a proteid insoluble in dilute acids 
and alkalies. 
(b) In proving that the aleurone-grains of oily seeds contain no oil, we have already 
seen that it must be present in the matrix. The doubt which arises from the first 
glance at sections of oily seeds, whether the great mass of oily matter can find space 
in the interstices between the grains, can be settled by calculation ; for if spheres 
(the grains may be so regarded) are placed in an equal number of cubes forming 
part of one great cube, 47 '6 p. c. of the cavity remains unoccupied; and if the 
spheres are distant from one another only about one-third of their radius, 69*7 p. c. 
of the cavity is left, and this is more than is sufficient in oily seeds to take up the 
oily matter. 
Immediate proof can be given of the existence of oil in seeds which contain it by 
the appearance presented by dry sections; if benzol is added, the matrix disappears, 
while small quantities of proteids remain. With alcoholic tincture of alkanet the matrix 
becomes of a deep blood-red colour if it contains a considerable amount of oil ; but if 
the oily constituents of the seed are very small, the evidence cannot be obtained in 
this manner. 
If the oil is extracted from the sections by alcohol, and the aleurone-grains then 
removed by potash solution, a net-work remains behind in which the grains are replaced 
That T formerly considered them soluble in ether, was the result, as Pfeffer showed, of the 
containing a small quantity of water. 
' On the causes of the solubiUty in water see Pfeffer's treatise already cited. 
