CHRONIC INFECTIOUS DISEASES 105 



horses are to be tested, this method has a great 

 advantage over the subcutaneous one on account of 

 the short time expended in making the test. With 

 practice and sufficient assistance to control the 

 animals, "as many as several hundred horses can be 

 injected within an hour. The reaction manifests 

 itself by local symptoms, such as swelling of the 

 eyelid, conjunctivitis, lacrymation, and later a muco- 

 purulent discharge, which freely flows from the eye. 

 The reaction is typical at about the twelfth to twenty- 

 fourth hour after injection. This test is nov^ con- 

 sidered to be thoroughly reliable, but in a small 

 number of cases doubtful reactions may be met with ; 

 in these cases the animal should be subjected to a 

 subcutaneous test later. In non-reactors there may 

 be a slight swelling of the lower lid, but this is easily 

 distinguished from the intense inflammation and 

 muco-purulent discharge so typical of a positive re- 

 action. Should there be any suspicion that a seem- 

 ingly positive reaction was caused by some other 

 agent than the mallein employed, a second test should 

 be made on the other eye twenty-four hours later. 



Actinomycosis. — Actinomycosis is an infectious 

 disease of cattle, occasionally aftecting other domestic 

 animals and man, which manifests itself either in the 

 appearance of connective-tissue tumours or in chronic 

 processes of suppuration. 



Etiology. — The ray fungus, Strejitothrix actinomycrs, 

 and B, actinomyces. This is a very common disease 



