34 
Hereditary Diseases of Sheep and Pir/s. 
surfaces, where it gives rise to more acute symptoms, and causes 
much tenderness and pain of the abdomen. The lungs and 
bronchial glands also participate in the disease, though to a less 
extent than in adults. It does not, we believe, come within the 
scope of the present essay to notice the treatment of disease ; 
but we may mention that the treatment of tabes mesenterica is 
not generally very satisfactory ; for in this, as in all hereditary 
diseases, the chief and immediate cause defies removal. Good 
feeding — especially of an oleaginous kind — nursing, and atten- 
tion to general health and comfort, will often mitigate the 
malady and sometimes subdue it for a time, but exposure to any 
untoward circumstances will be very apt to cause its recurrence, 
or lead to the development of pulmonary consumption. 
When a scrofulous constitution presents itself prominently in 
an adult sheep, it is generally in the form of pulmonary con- 
sumption, or, as it is technically termed, phthisis pulmonalis. In 
this disease the tuberculous matter is chiefly deposited in the 
air cells of the lungs, or in the areolar tissue, and first appears 
as a dirty, greyish-yellow, glairy matter, consisting of imperfectly 
elaborated cells mixed up with granules. After a variable but 
usually short time, this deposit increases in quantity and in 
hardness, becoming of a cheesy consistence, and filling up the 
cavities of some of the air-cells to the obstruction of respiration. 
The consequent irritation causes a frequent cough, which is at 
first clear and unaccompanied by apparent pain, but which after- 
wards becomes short, difficult, and evidently painful. In this 
stage percussion yields a dull sound, and auscultation discovers 
a harsh noisy kind of breathing ; but such indications vary 
much in the different stages of the disease, and can only be pro- 
perly understood and appreciated by the well-trained ear. The 
number of respirations is increased to about five-and-twenty per 
minute — a natural provision for the oxidation of as much blood 
as possible by the parts of the lungs still remaining sound. The 
pulse, which in sheep may be felt either over the heart or in 
some of the larger arteries of the limbs, is generally about 80 — 
weak, compressible, and easily accelerated by any kind of excite- 
ment. The appetite is capricious, and rumination performed 
very imperfectly, if at all. Such symptoms may continue with 
very little variation for many weeks or even months. During 
this time the tubercular deposits may soften and lose by absorp- 
tion their more fluid and liquefiable parts, leaving dry, shrivelled, 
chalky masses ; or during the progress of softening and con- 
sequent separation from their previous connexion, or by ulcerative 
action affecting the walls of the cavities thus formed, hemorrhage 
arises from the exposed blood-vessels — an occurrence, however, 
which is rare among the lower animals. Where neither of these 
