EDITORIAL OBSERVATIONS. 
233 
A new field of investigation is thus opened up for the pro- 
fession, namely, that of analysing this description of food ; 
and amply will it repay its cultivation. Chemistry and the 
microscope are the chief, if not the only, implements, so to 
speak, which will be required. On the authority of Herapath, 
we have it stated, that the microscope surpasses any other 
method of arriving at a satisfactory conclusion. Speaking of 
the plan to be adopted, he says, <e it consists in treating the 
cake, previously broken up into small pieces, with repeated 
portions of boiling water, and squeezing the insoluble re- 
mainder in a linen cloth, so as to obtain the husk of the seed 
in a separate state, and then to act upon the latter with hot 
dilute nitric acid, and examine its structure under a micro- 
scope. By means of the nitric acid, the starch, grains, &c., 
are dissolved, and the husks themselves are rendered so 
transparent, as to readily admit of their structure, and the 
form of their constituent cells, being observed. The form of 
these cells in the husks of the various oleaginous seeds is so 
essentially different, that a simple examination by this pro- 
cess will immediately convince us, that a better means of de- 
tecting the adulteration of oil-cakes could not be devised. 
Thus, for example, the cells in the mustard-husk are very 
small, whilst those of the rape and linseed-husk are con- 
siderably larger, and differ from them in shape. The mus- 
tard-husk has, moreover, a hexagonal network of thicker tis- 
sue, which is very characteristic, and is not observed in 
either of the others.”* 
With regard to the feeding properties of rape-cake, practi- 
cal experience has shown that it is inferior to good linseed- 
cake, although in a chemical point of view it ought to be 
quite as nutritious. This probably depends on its hot and 
pungent taste, and also on the disagreeable odour it possesses, 
its oil having a great tendency to become rancid, and thus 
causing cattle to refuse to eat a sufficient quantity of it. Its 
nutritive properties no doubt are also impaired from its con- 
taining the seeds of many plants, which spring up with the 
rape. Throughout Belgium and France, where rape is 
* See February number of the * Veterinarian, 5 p. 96. 
