BACILLUS ACNES CONTAGIOS^ 101 



colour, finally becoming yellow, and consist of distinct individual cocci. 

 (Kitt considers the Botryomyces to be a variety of the Staphylococcus 

 pyogenes aureus.) 



In Gelatine Stab Cultures it forms greyish-white threads, with slow 

 liquefaction commencing at the periphery. 



On Potatoes it forms a flat yellowish coating. 



Pathogenesis. Rabe and Kitt inoculated horses with pure 

 cultures, and in four to six weeks genuine fibromas appeared. Mice 

 are immune. Sheep and goats exhibit inflammation of the skin ; later, 

 necrosis accompanied with oedema. Guinea-pigs die from septicaemia 

 changes. 



The parasite generally confines its ravages to its primary seat. 

 It may, however, migrate toward the lymph glands and into the 

 blood, when metastatic foci appear, usually localized in the lungs, 

 skin, etc. 



BACILLUS ACNES CONTAGIOS^ OF THE HORSE 

 (D1ECKERHOFF AND GRAWITZ). 



This disease is a pustular dermatitis known as contagious acne of 

 the horse, and is very readily transmitted to other animals. In 

 severe cases ulcerations and inflammation of the lymph vessels and 

 glands occur. It is easily distinguished from farcy by the cicatriza- 

 tion of the ulcers, and, moreover, the pustules do not occur in farcy. 

 It is distinguished from horse-pox or variola of the horse by the fact 

 that in variola the eruptions are always localized in the lips, nostrils, 

 and pasterns. It is further identified by the presence of the bacillus 

 discovered by Dieckerhoff and Grawitz in the pustules. 



Microscopical Appearances. Very small ovoid bacilli, 2 //, long, 

 occurring singly and also forming small chains. 



Motility . Non-motile . 



Staining Reactions. Somewhat refractory with ordinary stains, 

 but stains by the Gram method. 



Spore Formation . Ab sent. 



Biological Characters. In Gelatine 8tab Cultures white colonies 

 about the size of a millet-seed develop along the course of the needle. 



On A gar- A gar, white colonies develop very slowly. 



On Blood Serum, especially from horses and cattle (37 C.), in twenty- 

 four hours small white colonies develop on the surface of the medium, a 

 granular deposit being formed in the water of condensation. 



On Potatoes it exhibits no growth. 



