654 
LECTURE ON THE DISEASES OF CATTLE. 
horses their customary chaff and give it to those whom you have 
deprived of the hay, thus making a sort of exchange, you will find 
instead of deterioration a great benefit to be the result : the horses 
will have a much less tendency to swelled legs and to coughs, of 
which this is a frightful source. This is an evil which is not 
generally felt in the neighbourhood of London, because the greater 
part of the horses here are fed upon grass lands ; but in some dis- 
tricts this has been the method of feeding farm-horses from time 
immemorial, and it is still generally retained. 
Let me explain why it is that food thus given has such an in- 
jurious influence on the animal. When food is taken into the 
mouth it has to be ground, as you would grind any thing into 
powder in a mill. An important thing connected with the process 
is the saliva or spittle of the animal. This is poured out in a large 
stream on each side of the mouth; and the food, being mixed up 
with it into a pulp, passes thus into the stomach. The quantity of 
saliva during the twenty-four hours l estimate at several quarts. 
T am speaking of cattle and horses ; it will be in the same propor- 
tion for other animals. This secretion is of an alkaline nature. 
Being mixed with the food, I repeat, the whole passes into the 
stomach. You there find a secretion known by the name of the 
gastric juice; and a change there takes place, which is complete 
so soon as the food has passed from the stomach into the intes- 
tines. In this last stage it is mixed with a secretion, or rather an 
excretion, called the bile ; a separation then takes place between 
the digestible and the indigestible, and while jthe former is 
absorbed, the latter passes away in the shape of faeces. I need 
hardly tell you that, if food instead of being masticated is bolted, 
disease must ensue ; and it is necessary that means should be 
adopted to prevent this. 
Now, so far as concerns those animals who perform a double 
mastication, the food is ground into pulpy masses ; and, having 
passed into the proper receptacle, it is again finely ground with a 
fresh supply of saliva. Now, Nature would not have made these 
two provisions were they not essential for the well-being of the 
animal. If you give an animal food which is not sufficiently 
ground or mixed with the due proportion of saliva, it will not 
thrive. This is the reason why horses will not thrive upon 
barley; there is not a sufficient quantity of saliva to render the 
gastric juice capable of acting upon such food to the necessary ex- 
tent. Let me here say that it is necessary not only to attend to 
the quality, but to see that there is the due quantity of food ; for 
unless the organs of digestion are supplied with a sufficient 
quantity, digestion cannot go on properly, and disease will result. 
I am very much disposed to consider that the feeding of swine 
