132 
ON THE EXTERNAL CAUSES OF DISEASE. 
30^/i.—She went to her work, which she has since followed 
without relapsing. 
I had again to remark how quick the decoction was in its 
operation, as it frequently took effect during the time I was admi¬ 
nistering it [Does not this appear to argue in favour of absorp¬ 
tion by the mesenteric veins ?), and without producing any 
unpleasant consequence. Its effects are diuretic, and tonic; 
and it is by no means despicable as an anthelmintic. The last 
mare voided an immense quantity of terites during the time 
she took it. 
ON THE EXTERNAL CAUSES OF DISEASE. 
Mr, W. F. Karkeek. 
There be many good and healthful airs, that do appear by habitation, 
and other proofs; that differ not in smell from other aii^s .— Bacon. 
Dr. Johnson, alluding to the task of an author, says, ‘‘It 
is either to teach what is unknown, or to recommend known 
truths by his manner of adorning them;—either to let new 
light upon the mind, and open new scenes to the prospect, or to 
vary the dress and situation of common objects, so as to give 
* them fresh grace and more powerful attractions.’’ 
It has been before stated that the writer lays little claim to 
originality ; but if in his progress he should describe such scenes 
to the readers of The Veterinarian, as to tempt them again 
to return and take a second view of things hastily passed over, 
his intentions will have achieved their entire consummation ; 
he shall then think his leisure usefully employed—his time for¬ 
tunately bestowed. 
The atmospheric air must be considered in two points of view; 
viz. in its chemical composition and properties, and in its medicinal 
relation, as far as it regards the condition of health and disease. 
But prior to our entering on this subject, it will be necessary 
to make a few preliminary remarks on an animal body. 
An animal body may be considered as a very complicated 
machine, made up of various parts, each differently constructed 
from the rest, and possessed of different feeling and manner of 
acting. The different parts of this machine are called organs, 
and the whole taken together we call the system. Every thing 
around living bodies tends constantly to their destruction; and 
to this influence they would yield, were they not gifted with 
some permanent principle of reaction. This principle is their 
life; and a living system is constantly engaged in the perform¬ 
ance of functions whose object it is to resist death. 
