K. F. MEYER 615 



agar. Gelatin is not liquefied; in broth stalactites or flocculent sediment is regularly formed. 

 As a rule, the strains render milk alkaline and ferment, dextrose, galactose, levulose, maltose, 

 arabinose, trehalose, xylose, rhamnose, mannite, and glycerol with the production of acid 

 but no gas. The action on adonite, dextrin, and salicin is irregular (Christiansen, Christen- 

 sen).' For a definite identification the agglutination tests with specific sera must be used. 

 With the aid of this technique Stockle^ has recognized one culture isolated by Branch as a 

 typical strain of B. pseudotuberculosis {rodcntium). 



The experimental infection of guinea pigs, rabbits, mice, and field rats by any route is 

 successful, although the guinea pig strains of B. pseudotuberculosis (rodcntium) produce 

 rarely generalized lesions in rabbits. On subcutaneous injection merely local infiltrations and 

 necroses are noted. Guinea pigs succumb in from eight to fifteen days (dosage, 400,000,000 

 organisms) to an infection per as, by inhalation or by subcutaneous application. White rats 

 are generally considered non-susceptible, but strains have been encountered (Meyer and 

 Batchelder) which produce an active disease by the intraperitoneal route. A toxic substance 

 has been demonstrated in the broth cultures by a number of workers (Dessy, also the writer). 



In the course of an epidemic the diseased animals may, according to Ramon, 

 exhibit three types of clinical manifestations: septicemia, fatal in twenty-four to 

 forty-eight hours' classical form with emaciation, diarrhea, and death in three to four 

 weeks, and the glandular form with lymph adenopathy of the cervical and thoracic 

 nodes. Since the differential diagnosis is difficult, serological (agglutination, Pfeiler) 

 or complement fixation (Bachmann)^ or intracutaneous hypersensitiveness tests 

 (Bachmann, Dessy)-) have been recommended. At autopsy the enlarged mesenteric, 

 iliac, periaortic, and occasionally inguinal lymph nodes are transformed into a mass 

 of thick, yellowish pus, and fibrous tissue together with an enlarged spleen and liver 

 both studded with whitish nodules are generally considered pathognomonic for this 

 infection. The intestines, the omentum, the kidneys, and the uterus may also reveal 

 scattered small abscesses. In a few epidemics the lungs were found similarly involved, 

 but as a rule the abdominal viscera are primarily diseased. It is of interest that his- 

 tiologically giant cells are usually absent and epithelioidal cells are seen only in rare 

 instances. 



The natural mode of infection occurs probably by way of the digestive tract 

 (Ramon, Branch). In a small epidemic started in an isolation room by the introduc- 

 tion of guinea pigs and mice injected with a highly virulent strain, the writer was 

 able to record many fatal contact infections. The primary lesions were found in the 

 intestines and the mesenteric lymph nodes with little or no involvement of the 

 thoracic and subcutaneous nodes. In a number of animals the active disease ended 

 in a chronic carrier state. Nothing definite is know^n regarding the epidemiology of 

 this infection, and therefore no suggestions concerning its control can be given. Van 

 Saceghem5 successfully immunized guinea pigs with i cc. of a broth culture heated to 

 60° C. while Dessy was unable to produce an active immunity with killed cultures or 

 toxins, although the treated animals developed a state of allergy. 



' Christensen, N. P. C: reprint from the Kgl. Velerinaer-og Landbohjskohs Aarsskrift. 1927. 



^ Stockle, J.: unpublished observations. 



^Bachmann, W.: loc. cit. 



^ Dessy, G.: op. cit., 4, 133. 1925. s van Saceghem, R.: loc. cit. 



