Two impor- 
tant groups 
of food 
compounds. 
Nitrogenous 
compounds. 
26 ON THE PLACE OF FISH IN 
ference, as to what they do in the body, between the 
compounds which contain N, and those which do not, 
that this forms the ground of division into two great 
groups. 
It is customary to speak of the CH O compounds 
as Carbon compounds, and C HON compounds as 
Nitrogen compounds. It has often been found that 
in some minds a confusion exists between the element 
Carbon itself and carbon compounds, and the element 
Nitrogen and nitrogen compounds. It would avoid 
this confusion to adopt the names “CHO com- 
pounds,” and “C H ON compounds,” but it would be 
an untried innovation, and the usual custom of using 
the names is followed. 
The important point to notice is that both groups 
contain C and H, and the distinction of names is not 
meant to imply that one group contains only Nitrogen 
and the other Carbon. Both have C and H, which 
produce heat and force, but the nitrogenous group 
only can, so far as we know, in addition to producing 
heat and force, form muscle. 
It will, of course, not be forgotten that though 
muscle cannot be formed without nitrogenous com- 
pounds, the mere fact of having a plentiful supply of 
them in the blood will not form muscle. A muscle 
increases only by use—use, with a plentiful supply of 
nitrogenous compounds in the blood. The importance 
of fish diet in relation to this plentiful supply will be 
seen from the table on p. 32. 
It is found that all the NITROGENOUS COMPOUNDS 
used as food have very nearly the same proportions 
of C, Hand N. The elements in them are differently 
grouped, and to the scientific chemist they present 
