210 
THOMAS WALLEY. 
The heat and force-producing elements, though existing only 
in very small proportion in normal blood, are vitally as necessary 
to the well-being of the system as are the proteids. If they are 
deficient and cannot be obtained from the food, they must be got 
from the tissues—especially the fat—and if they cannot be ob¬ 
tained at all, heat production ceases and life is extinguished. 
Fat is the first to become absorbed and burnt up in wasting 
diseases, but it is followed, or perhaps sometimes preceded, by 
the consumption of the proteids. 
Excess of carbonaceous elements in the form of fat produces 
debility and interferes with the vital activity of the cells of the 
body, as well as predisposes to stagnation. Moreover, if this ex¬ 
cess is kept up, the cells of the tissues of important organs become 
firstly, infiltrated with fat; secondly, actually transformed into 
fat. Independently of carbonaceous matters being required for 
respiration and production of heat, fat constitutes the basis of 
muscle, and no animal can thrive or even live if deprived thereof. 
Such elements frequently save the more important proteids from 
oxidation or burning. 
Of the salts of the Hood it cannot be said that one is more 
important than another. Chlovide of sodiuTu (common salt) is 
probably the most necessary for the preservation of health, and 
its withdrawal, or its absence from the blood, is followed by the 
gravest consequences. Salt (sodium) is required not only for the 
blood, it is necessary to the formation of the gastric juice and of 
the bile and for the digestion of albumen; and of the fact of its 
presence in the blood I cannot give a better proof than that 
which may be obtained by tasting the perspiration or the tears. 
Nature cries out for it, as is shown in the wandering of the deni¬ 
zens of the wilderness in search of it, and it is provided for them 
in the form of “ salt licks.” 
Excess of salt is highly injurious, interfering as it does with 
the skin glands, and with the blood, inducing important skin dis¬ 
eases— e. g ., scurvy in man and eczema in certain animals, partic¬ 
ularly in dogs. 
That potash is necessary is proved by the fact of its forming 
a constituent part of the material food of animals, viz., vegetables. 
