HORSE SICKNESS IN SOUTH AFRICA. 
35 
the blood is dark in colour and coagulates imperfectly. 
On examining it with a microscope, in all cases where I have 
been enabled to do so, I have invarably found Bacteria 
present. 
Chest .—This cavity often contains a quantity of straw- 
coloured fluid on both sides; the lungs are found to be in¬ 
tensely gorged and very heavy, and along the edges and in 
patches a large quantity of yellow lymph is deposited beneath 
the pleural covering; on cutting into them blood and serum 
flows freely from the cut surfaces as well as yellow frothy 
mucus from the tubes; the interlobular space is filled with 
fluid. The pericardium contains a quantity of straw-coloured 
fluid also; the heart I have sometimes found soft and flabby, 
and it usually contains small clots remarkably soft; in the 
left side there are invariably black patches (ecchymosis) beneath 
the lining membrane, more or less extensive. 
In the form termed Throat-sickness there is great swell¬ 
ing of the throat between the lower jaws, involving the larynx, 
&c. I have not seen this form myself, but I am told that 
upon cutting into it the parts are very black. 
In those cases where the lungs are only lightly affected, and 
there are no external swellings, death appears to result from 
the intensity of the fever. 
Contagion and Infection. 
This disease is not considered contagious nor infectious. 
Whether it can be produced by inoculation I have not yet 
been able to determine. 
Incubation. 
The period of incubation is not known. I have no doubt 
that it is often very short, but there is reason to believe that 
in some instances it is in the system for some time before 
showing any outward symptoms, only waiting for conditions 
favorable for its development. 
Causes. 
The causes giving rise to this disease are very obscure; the 
opinion of the Dutch and that of the Colonists generally is, that 
it is due to miasma, and that it is contained in the dew, so 
that if a horse is not turned out to graze till the dew is off the 
grass, and brought in before it falls in the evenings, he is safe. 
This practice is very good, but as a matter of fact, it does not 
prevent the disease, besides which many die from horse- 
sickness that are stabled and not allowed to graze, but fed on 
grass cut for them. 
