1882.] 
The War against Agriculture . 389 
physiologically. Let us take the instance of milk: here we 
have milk-fat, milk-sugar, caseine, albumen, and nucleine, 
besides galaCtine, laCtochrome, certain mineral salts, and a 
number of minor ingredients. These various substances, 
though they are chemical compounds, are not combined 
together chemically, but exist in a mixture. The physio- 
logical action of the milk, as food, depends not upon any 
one principle which might be extracted and consumed sepa- 
rately, but upon the whole in their ordinary proportions, 
upon their modifying aCtion upon each other, upon their 
physiological condition, and their structure. 
We might in the same manner examine a grain of wheat, 
an apple, or a mutton-chop, and find that its value as food 
depends not on its chemical individuality, but on the joint 
presence of a number of substances which must be in cer- 
tain conditions. Thus suppose we were to undertake a 
comparative analysis of two beef-steaks, the one tender and 
the other tough, we should doubtless find their composition 
substantially one and the same. Yet if a man eats the 
tough steak he will suffer more or less from indigestion, 
whilst from the tender steak he would experience no un- 
pleasant consequences. 
If we turn from articles of food to textile fibres, such as 
flax, hemp, or cotton, we shall find that though consisting 
essentially of one and the same chemical principle, cellulose, 
yet when freed from all foreign matter they still exhibit 
differences of properties which fit them for different uses, and 
which depend not on chemical distin( 5 tions, but on structure. 
If we now compare these two great classes of natural or- 
ganic products, we find certain very important practical 
distinctions. Class I., the dyes, medicines, perfumes, &c., 
are generally much more profitable to the farmer and planter 
than Class II., the foods, fibres, &c. Again, Class I. is 
mainly produced in tropical or subtropical climates, whilst 
Class II. may be raised even in temperate and subarctic 
regions. 
A more important distinction follows : the bodies we have 
included under Class I., being definite chemical compounds, 
their artificial production is at least conceivable. Suppo:e 
we obtain, through the vital aCtion of a plant, a combination 
of oxygen, hydrogen, carbon, and nitrogen, in certain pro- 
portions : we may possibly get the same elements to combine 
together in the same proportions without the intervention of 
the plant, or, in other words, to make the compound in 
question artificially. In other cases we may obtain the same, 
or a closely analogous product, through the instrumentality 
