LIVERPOOL VETERINARY MEDICAL ASSOCIATION. 143 
In addition to the above, however, we know that there is another 
class of substances required for the maintenance of life, viz. starch, 
sugar, gum, &c.; these are convertible in the animal system and are 
necessary for carrying on of respiration, but above all for the 
accumulation of fat, which is again convertible to other purposes, 
such as heat, &c. 
Secondly.—The part fibrin performs on the animal economy. 
Fibrin exhibits more vital properties than any other fluid com¬ 
ponent of the blood,—so much so, that if separated from other 
constituents of the blood, it is capable alone of assuming the 
condition of an organized tissue. It was natural to suppose that 
this was the pabulum from which materials were drawn for the 
growth and development of the animal body ; but from further 
demonstrations, both structural and chemical, it has been shown 
that fibrin is rather in a state of a fibro-gelatinous texture, than a 
fibro-albuminous class’ because the fibrous network which is formed 
by its coagulation bears a stronger resemblance to the white fibrous 
tissue than any other texture of the body, whilst, chemically, fibrin 
differs from the albuminous class with its relationship to gelatine ; 
the only difference being, according to Lehmann, that fibrin contains 
1‘5 more oxygen in every 100 parts than albumen does. Nearly 
all the changes produce by various agents in coagulated albumen 
may be repeated with coagulated fibrin, with no greater differences 
of result than may be reasonably ascribed to the differences in the 
mechanical properties of the two substances. The principals are 
that fibrin, immersed in acetic acid, swells up and becomes trans¬ 
parent, like gelatine, while albumen undergoes no such apparent 
change; and that deutoxyde of hydrogen is decomposed when in 
contact with coagulated fibrin, but not with albumen. Gelatine 
exists very largely in many classes of tissue, such as the skin, 
hoofs, cartilage, and the soft parts of bone. Most chemical physio¬ 
logists have agreed that the substance forming gelatine, cannot, 
under any circumstance, be retransformed within the animal body 
into any kind of nutritious material, excepting to gelatinous tissues 
again. It is easy to understand, then, how the blood of young 
animals may become destitute of fibrin, for the gelatinous tissues in 
young animals form by far the largest proportion of the whole 
body, than they do in the adult animal; therefore a constant 
demand is made on the fibrin of the blood to meet the requirements 
of material, for the rapid growth of gelatineous tissues in the young 
animal. Whether fat or lean, then, the young are liable to be 
attacked with this disease; the daily food supplied to the animal in 
good condition, and thriving as well as one could wish, has been 
rich in material adapted for the production of fat, starch, oil, &c., 
but deficient in plastic or nitrogenous elements of nutrition. 
Whilst animals that are attacked in a low condition, their food as 
not only been deficient in quantity, but also in quality, being desti¬ 
tute of the elements of protein, and also those necessary to produce 
fat. Some exciting cause passes over the animal, and he becomes 
a victim of the disease. 
