146 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



properties with that isolated in this laboratory in 1920 from swine 

 urticarial lesions. 



In Europe it is a well-known fact that the swine erysipelas germ 

 is responsible for certain types of arthritis in swine. During the last 

 year some bacteriological work has been done on material from 

 polyarthritis cases in swine. In one instance Bacillus ci^ysipelatis 

 suis was isolated from an infected joint. « 



DIPHTHERIA ANTITOXIN IN BLOOD OF NORMAL HORSES, 



It was found that about 80 per cent of serums from normal horses 

 contained sufficient protective properties in quantities of 1 cubic cen- 

 timeter to protect guinea pigs against two fatal doses of diphtheria 

 toxin. That this protective property was due to specific antitoxin 

 was demonstrated by the application of the Schick test to a number of 

 horses. The results of this work were reported in the Journal of the 

 American Veterinary Medical Association June, 1922, page 286. 



COMMERCIAL RAT VIRUSES. 



Twelve commercial rat viruses were tested in caged rats both by 

 feeding and by inoculation. A wide range of efficiency was demori- 

 strated as between different products or different samples of a given 

 product. In general the commercial viruses did not accomplish what 

 was claimed for them. 



A study of the Danysz bacillus, which is used in the preparation of 

 commercial rat viruses, showed that its virulence could be enhanced 

 in a measure by rat inoculations, and that the recovered organism, if 

 repeatedly transferred upon ordinary media, would rapidly decrease 

 in virulence. Feeding and inoculation tests indicated its nonpatho- 

 genicity for ordinary domestic animals and laboratory animals other 

 than rats or mice. 



OTHER INVESTIGATIONS. 



Lesions in the spleens of swine, resembling somewhat in gross 



appearance the lesions of tuberculosis, were studied under the micro- 



, scope. The presence in some cases of small bodies closely resembling 



actinomyces led to the conclusion that the affection was actinomycosis. 



A study of Lange's colloidal gold test applied to the spinal fluids 

 of animals dead of various diseases was made, with particular atten- 

 tion to dourine. A variety of curves were obtained, many of which, 

 however, bore considerable similarity. 



Stock cultures of more than 100 microorganisms are maintained in 

 the Pathological Division for the purpose of supplying the needs of 

 biological houses, research workers, and educational institutions. 



INVESTIGATIONS OF CHANGES IN MEATS. 



In the last annual report reference was made to a condition ob- 

 served in pork hams, particularly cooked hams, in which there was a 

 complete breaking down of the musculature, resulting in a soft, pasty 

 condition. Microscopical examination disclosed the presence of nu- 

 merous small parasites (sarcosporidia). In a large percentage of 

 such cases the only diseased condition accompanying the heavy par- 

 asitic infestation was a verj' marked degeneration of the muscle tissue,* 



