INFECTIOUS PLEURO-PNEUMONIA. 



239 



Filtered cultures are said to confer immunity for six months, and 

 raising the temperature of filtered cultures increases the strength of 

 the substance which gives immunity (Klemperer). The blood serum 

 of immune animals can confer immunity on other animals, and, it is 

 said, will arrest the progress of the disease produced by injection 

 of healthy animals with virulent cultures. The cultures contain a 

 proteid body, for which the name pneumo-toxin has been suggested, 

 and anti- pneumo-toxin has been isolated from immunised blood 

 serum. 



INFECTIOUS PLEURO-PNEUMONIA. 



Infectious pleuro-pneumonia is a highly infectious disease 

 peculiar to cattle ; it is characterised by rise of temperature and 

 exudation into the lungs. It is often fatal, and sometimes exists in 

 an extremely chronic form. It is believed to have been unknown in 

 England previously to 1840, and is supposed to have been introduced 

 from Holland, where in one year it destroyed seven thousand cattle. 



FIG. 118. ACUTE CATARRHAL PNEUMONIA (Ox). 



<(, Coagulated mucus with catarrhal cells (c) embedded in it ; b, catarrhal cells 

 sprouting from alveolar wall, x 480. (Hamilton.) 



The disease cannot be conveyed artificially. A living, diseased 

 animal must be the medium of infection. The disease is apparently 

 only communicated by cohabitation. Brown injected large quanti- 

 ties of lymph from diseased lungs into the jugular vein, into the 



