BUREAU OF ANIMAL INDUSTRY. 513 
Schiitz, in his investigations of swine plague in Germany, was able 
to reproduce the disease by exposing pigs to the spray from culture 
liquids simply because he had a more virulent microbe to deal with. 
He produced, for example, a general septicemia in pigs by the sub- 
cutaneous injection of cultures. Numerous subcutaneous inocula- 
tions made with cultures at the experiment station of the Bureau 
have in no case produced septicemia. We must not expect any 
microbe to grow in the blood and internal organs of healthy inocu- 
lated animals when it appears there only in rare instances and in 
very few numbers in animals spontaneously affected with the specific 
lung disease, and moréover with the whole system greatly debilitated 
thereby. In his investigations of infectious pneumonia in horses 
Schiitz* reproduced the disease with cultures of the specific microbe by 
direct injection of culture liquid into the lungs through the walls of the 
thorax. In a second experiment made by spraying a large quantity 
of culture liquid through a tracheotomy tube directly into the 
bronchi the lesions found on killing the animal proved less positive. 
Careful observations of the lungs in pigs which have died of hog 
cholera, of those which have been killed, apparently in good health, 
and of those of very young animals which died of exposure or lung 
worms, lead us to conclude that unless the bacteria of swine plague 
happen to be of exceptional virulence, some slight lung disease, such 
as atelectasis or lobular broncho-pneumonia, must furnish the starting 
point from which the remainder of the lung tissue is attacked. In 
the preceding article on hog cholera this has been dwelt upon more 
atlength. 'Thereit has been shown that in at least one season of the 
year, the fall, collapse and lobular pneumonia, lung worms, and bron- 
chitis are very common in young animals. Whenan epizooticis very 
severe, and such seem to be quite rare, the healthy lungs of even 
adult animals may be attacked. Of this state of affairs the epizootic 
described furnishes a good illustration. 
SOME OBSERVATIONS ON THE GENERAL CHARACTER OF SWINE 
PLAGUE. 
To understand the character of this disease, its mode of invasion 
and particular seat, a brief description of the pig’s lung is necessary: 
When inflated through the trachea after the sternum is removed, and while it is 
still in its natural position in the thoracic cavity, it will be observed that the surface 
resting against the ribs laterally is the most extensive. That surface resting upon 
the diaphragm comes next, while the ventral aspect is the smallest. 
The right lung is made up of four lobes; the left has only three. (In text-books 
on anatomy the left lung is considered as being made up of only two.) 
In both there is a large principal lobe resting upon the diaphragm and against the 
adjacent thoracic wall. This lobe forms the major part of eachlung. Theremain- 
der, occupying the anterior (or cephalic) portion of the cavity, is made up of two 
small lobes, one extending ventrally (or downward in the standing position of the 
animal) and in the expanded state covering the heart laterally, the other extending 
towards the head and overlapping the base of the heart. These small lobes may be 
denominated the ventral and cephalic lobes, respectively. The right cephalic lobe 
is longer and more distinct from the ventral lobe than the corresponding left ce- 
phalic. Wedged in between the two principal lobes and resting on the diaphragm 
is a small lobe, pyramidal, belonging to the right lung (azygos lobe). This lobe 
rests on the left against the mediastinal membrane, and on fhe right it is separated 
from the right principal lobe by a fold of the pleura passing from the ventral ab- 
* Die Ursache der Brustseuche der Pferde. Archiv fiir pathologische Anatomie 
(1887) CVIT, p. 856. Archiv fiir wissenschaftliche und praktische Thierheilkunde 
(1887) XIII, p. 28. 
AG 87 33 
