LACHRYMAL DISEASES. 189 
AFFECTION OF THE HAW. 
In the inner corner of the eye is a semilunar fold of the mucous membrane, 
which is called the membrana nictitans or the haw, and resembles somewhat the 
third eyelid of birds. Its purpose is to protect the eye and sweep dust and 
foreign bodies from the eyeball. 
It is subject to inflammations, which may be induced by injuries, irritants, 
faulty management, and likely by constitutional diseases; and such trouble 
existing, the following symptoms are noted: Redness, swelling — which is some- 
times of such extent as to affect the sight — profuse flow of tears, and more or 
less pain. 
Generally only one eye is affected, and when both are involved the assump- 
tion is justified that the trouble is probably secondary to some disturbance within 
the system; and as a rule it is then found that the general health of the victim 
is poor. 
Bathing with warm milk is the usual treatment of kennelmen, and this appli- 
cation is of the efficiency of tepid water, and no greater. If as soon as the 
swelling appears a solution of borax and camphor water, ten grains to an ounce, 
or one of the sulphate of zinc and water, three grains to two ounces, is freely 
used, the affection should yield readily. In event, however, it resists these 
applications, it will be necessary to snip the membrane with blunt scissors. 
This can be easily done, though it were best to entrust the operation to 
a physician. 
A few drops of 5 per cent solution of cocaine should first be dropped into 
the eye. Then the membrane should be pierced by a light suture needle and 
a thread drawn through, by means of which it should be lifted up as far as 
possible from the eye. Now with the scissors a goodly piece of the membrane 
through which the thread runs should be cut away.. 
To bathe occasionally with cold water will be all the after-treatment required. 
LACHRYMAL DISEASES. 
The tears are produced in glands situated at the upper part of the orbital 
cavity, which open by ducts upon the surface of the conjunctiva between the 
eyeball and upper lid. The office of the tears is to keep moist the parts over 
which they flow, and preserve the transparency by preventing their surfaces from 
drying up. 
The movements of the lids spread the tears uniformly over the eyeball; 
they are then conducted off through the lachrymal canals, which finally dis- 
charge into the nasal passages. 
