142 LIVERPOOL VETERINARY MEDICAL ASSOCIATION. 
of an early spring, in which the grasses are forward and fall of 
moisture,—this is proved by the best of the herd manufacturing, as 
they do, the largest quantity of rich stimulating blood, often fall 
first to its ravages ; whilst others whose growth, after weaning, or 
from any other cause, has received a sudden check, and which are 
beginning again to thrive, are also prone to suffer from this disease 
—probably because the blood-vessels, not having recovered from the 
previous weakness in which they participated with the system at 
large, give way when subjected to the increased pressure of larger 
quantities of richer blood. Those who have directed their attention 
to the subject, have agreed that the principal proximate causes of 
Quarter Ill, are a deficiency of the fibrin and the otherwise vitiated 
state of the blood. Now, before proceeding any further with the 
causes of this disease, let us first of all consider the formation of 
the fibrin; and, secondly, the part fibrin performs in the animal 
economy. 
Fibrin is found most abundantly in the blood and the more 
perfect portions of the lymph and chyle. It is very doubtful, how¬ 
ever, whether fibrin, as such, exists in these fluids; that is to say 
whether, it is not itself formed at the moment of coagulation. 
Recently there has been some very interesting experiments made, to 
make it probable that the idea of fibrin existing in a liquid state in 
the blood is a mistaken notion of its real nature, and that probably 
it does not exist at all in solution as fibrin, but is formed at the 
moment of coagulation by the union of two substances which in 
the blood exist separately, and which Schmidt proposes to term 
fibrino-plastic and fibrinogenous. We are all aware that the food 
is the principal source from which compounds of the blood, and 
consequently all the various organs composing the body are 
abstracted. The digestive apparatus of ruminants is not very 
simple; their food consists of vegetable products, and chemical 
researches have shown that all such parts of vegetables as can give 
nourishment to animals contain certain constituents which are rich 
in nitrogen; and the most ordinary experience proves, that animals 
require for their support and nutrition less of these parts of plants 
in proportion as they abound in nitrogenous constituents. These 
important products of vegetables are especially abundant in the 
seeds of different kinds of grain and in the roots and juices of what 
we commonly call vegetables. This is generalty styled the plastic 
element of nutrition, and composed of vegetable fibrin, albumen, 
and casein. Mulder says that these substances are found in all 
parts of plants—in the roots, stems, fruit, leaves, and sap, and form 
different compounds with sulphur and phosphorus, or with both. 
Thus the vegetable fibrin, albumen, and casein are the basis of the 
animal system, and enter into the various combinations therein 
produced. These considerations induced Mulder to give to the 
product of vegetable fibrin, albumen, and casein, the name of 
protein. The blood, or the constituents of blood are consequently 
compounds of this protein, with variable proportions of inorganic 
substances. 
