78 
i 
PROGRESS OF VETERINARY SCIENCE AND ART. 
Respecting the uses of saliva, M. Bernard has concluded, 
from iriany ingenious experiments on the horse, that it 
performs a purely mechanical office ; the drier the aliments 
the greater the amount of saliva secreted during mastication 
arjd" required for deglutition. Bernard establishes, lstly, 
*fnat dry provender absorbs about four or five times its weight 
of the mixed fluids that enter the mouth; <2dly, that dry 
feculent food, such as oats and barley, absorbs a little more 
than its weight of mixed saliva ; 3dly, that green food takes 
up a little less than the half of its weight of the same liquid ; 
4thly, and lastly, the worst form of feculent food, such as 
moist bran,&c., do not take up any noticeable amount of saliva. 
The quantity of saliva varies according to the length of time 
engaged in the mastication of food. 
M. Bernard has sought by experiment to confirm or refute 
the opinions emitted by certain chemists respecting the 
peculiar action of saliva on starchy matters, converting them 
into dextrine and grape sugar. He finds that this property 
is not enjoyed by the pure secretion of any of the salivary 
glands taken alone, but that it belongs to the mixed saliva 
and other organic fluids, though these may be morbid 
products. The diastase of die saliva appears, therefore, to 
owe its existence to the decomposition of the ptyaline and 
of other products found mixed with the saliva. This appears 
established as a fact by the strange observation made of the 
more speedy convertion of starchy matters by the saliva 
when the mouth is the seat of inflammation. Moreover, the 
contact of starch with a mucous membrane suffices to deter- 
mine this transformation ; and M. Bernard believes, therefore, 
that the chemical action of saliva is an accidental rather than 
its essential use. And, adopting the views of the ancients, 
he considers the saliva to have a purely mechanical office to 
perform. 
M. Colin must next engage our attention as the results 
he has arrived at by experiment differ in some small particulars 
from those of Bernard. Such differences may and do 
doubtlessly depend on the fact that Bernard has studied the 
salivary secretion in the dog and Colin chiefly in the horse 
and ox. 
The secretion of the parotid is said by Colin to be entirely 
suspended in the horse during the period of abstinence, but 
that in ruminants it is continued even when food is not taken 
into the mouth. 
On the submaxillary secretion, Colin’s account agrees with 
that of Bernard ; but he alludes to a distinctive character in 
the ox, viz., to its suspension during the second masti- 
