50 THE MICROSCOPICAL NEWS. 
recognize it, we treat all the crystals with a concentrated solution 
of asparagin, in which this substance alone remains crystallized. 
It should be observed that the tissue in which it is to be studied 
ought to be in active life, since asparagin, which is an acid of 
bimalate of ammonia, constitutes a product of secretion, as it were 
the urea of plants. 
Znulin.—Solid inulin can be obtained in the cells in two different 
conditions ; in the amorphous or the crystalline. Desiccation 
causes the precipitation of this substance, which previously existed 
dissolved in the cell-sap ; it is most frequently amorphous. Never- 
theless, when desiccation is very slow it crystallizes. 
Prolonged maceration of the organs which contain the reserve- 
materials in alcohol causes the formation of sphero-crystals of 
inulin. When sections are made of the tissue thus prepared a 
little acetic acid is added, and they are put in glycerin. 
The alcohol used must be diluted with water. It is advantageous 
to reduce imperceptibly, by evaporation, the quantity of water 
added to the alcohol, and to keep up the level of the liquid in the 
vessel by adding to it gradually absolute alcohol. 
When there is not time to allow the organs to remain in the 
alcohol before making sections, the sections themselves can be sub- 
jected to the action of either absolute alcohol or ether. In this 
case a deposit of amorphous inulin is obtained. 
Saccharose.—The saccharoses are insoluble in absolute alcohol. 
It is, therefore, sufficient to treat the saccharine cells by this agent 
in order to produce the crystallization of the saccharose. Bonnier* 
has often had recourse to this process in the examination he has 
made of the nectaries. By way of verification he treated the 
soluble portion of the tissue with 80 per cent. alcohol and with 
ether ; he then saw crystals of the same form appear in the liquid. 
Sections made transversely to the saccharine tissues can also be 
allowed to dry. In evaporating, the cell-sap leaves the saccharoses 
in the form of stellate crystals, the crystallographic system of which 
it then becomes possible to recognize. 
Aleurone.—This is the place to point out the means of preserving 
from solution in water the proteid part of the aleurone grains. It 
is known that in several plants, the peony for instance, this portion 
of the grain is very soluble in water. It is rendered insoluble by 
first subjecting it to the action of an alcoholic solution of bichloride 
of mercury. It is on this very phenomenon that Pfeffer relies to 
establish the presence of a quarternary nitrogenous substance in 
the aleurone grain.} 
(Zo be continued. ) 
* ** Les Nectaires,” Ann. Sci. Nat., 1879. 
+ Pfeffer, Jahrb. f. Wiss. Botanik., viii. (1872). 
