396 Veterinary Medicine. 



slaughter. Age therefore and long and repeated exposure to the 

 infection must have favored extension of the disease, while the 

 prime of life and strong vigorous health proved no bar to infec- 

 tion. Indeed the disease has been seen mainly in fat sheep 

 killed for mutton. 



Causes. Bacteriology. The essential cause of this disease is a 

 short, stubby, round ended, ovoid microorganism. It is non- 

 motile, aerobic (facultative anaerobic), non-sporalating, stains 

 readily by Ziehl's, L,offler's and Gram's methods, is very suscep- 

 tible to the action of acids. It shows a remarkable polymor- 

 phism. It may be present as a coccus, a dipplococcus (dumb- 

 bell), or a club-shaped organism, the latter 1.3 to 1.6 /* long, by 

 0.4/11 thick. Though its growth is at first tardy in artificial 

 cultures, it proliferates much more freely in successive genera- 

 tions, on agar, glycerine agar, peptonized beef bullion, or blood 

 serum. It grows poorly on gelatine, as it does best at 37.5° C. 

 which melts the gelatine medium. It grows freely on potato 

 and in milk. It is not gas producing with sugars. The thermal 

 death point is 65° C. for 10 minutes. It resists frost, but is 

 killed by a 2.5 per cent, solution of carbolic acid for i minute, 

 or by a 0.25 per cent, solution of formalin for 6 minutes, or a 

 1 :20oo solution of mercuric chloride for 4 minutes. 



Exposure to limewater for 24 hours did not appreciably retard 

 subsequent growth, suggestive that the germ may be preserved 

 in limestone soils or such as are rich in organic matter. 



Animals susceptible Feeding experiments on Guinea-pigs 

 caused death in from five to eight weeks with caseous degener- 

 ation of the lymph glands. Inoculation of rabbits caused death 

 in from three to seven weeks, and feeding experiments in from 

 eight to ten weeks. Caseation of the lymph glands resulted in 

 both cases. Mice, pigeons and hens succumbed much more 

 slowly. Caseation of lymph glands followed intravenous and 

 subcutaneous inoculation in sheep, but not after feeding experi- 

 ments. 



Symptoms. The disease is usually overlooked during life be- 

 cause of the absence of definite symptoms. Nearly all the cases 

 studied have been studied post mortem, the sheep having been 

 killed in good condition for mutton, and without any suspicion 

 of illness. Inoculated cases have been found to fall off in con- 



