Although the changes due to lung-sickness are not restricted to the
pulmonary tissue, yet the lesions in the lungs are of sufficient value to be
of great help in diagnosing pleuro-pneumonia macroscopically.
1. The interstitia, ie. the interalveolar, the interlobwlar, and_peri-
bronchial connective tissues are the seat of a primary inflammation of
serofibrinous character. The chief changes due to inflammation take
place in the connective tissue, therefore pleuro-pneumonia can rightly
be said to be an cnterstitial pneumonia.
2. The disease follows the course of the lymphatic vessels very
closely and affect the lymphatic vessels in the first place; having recourse
to the microscopic examination, we must diagnose a lymphangitis
serofibrinosa.
3. The thickening of the septa (which can reach 8 cm.), and the
so-called marbling of sections have certainly some diagnostic value, pro-
vided that the histological details are in agreement.
One will never find the described stratified arrangement of cavities
and fissures in traumatic pneumonia, so common in cattle in consequence
of perforation by foreign bodies; quite independently of the total differ-
ence in histological details.
4. After sequestration has taken place diagnosis is no longer possible
except by microscopical investigation.
MicroscopicaL LESIONS IN THE LUNGS.
The specimens which were preserved as already mentioned in
formaline or Orth’s liquid, were examined in paraffine or celloidin sections,
after staining with haemalum-orange, Van Gieson, May-Grunwald Fischer,
Heidenhains-haematoxyline, fibrine staining after Weigert and Kockel*
or after Fraenkel} with Best’s carmine for glycogen elastic fibrillae after
Fraenkel and Mallory. Hach section was carefully analysed in order to
facilitate comprehension and to be able to make comparisons.
