680 EXPEEIMENT STATION EECORD. 



opinions of otliers relative to the disease caused in young pigs by Bacillus 

 voldagsen, tlie results of some tests are briefly mentioned (E. S. K., 31, p. 87). 

 A positive method for immunizing against the Voldagsen pest has been devised, 

 which consists of administering a vaccine. The disease is pi-evalent in Germany 

 and probably in Italy and Hungary. 



The significance of bacterial infection in hog cholera, R. R. Dinwiddie 

 (Arkansas Sta. Bui. 117 {1914), pp. 593-619) .—The author discusses the effect 

 of bacteria (secondary invaders) on the cycle of hog cholera, the effect of the 

 presence or absence in the serum of antibodies to bacterial infection, the sig- 

 nificance of Bacillus suisepticus, and related questions, and reports experiments 

 along these lines. 



By inoculation tests it has been previously found that virulent strains of B. 

 suisepticus may be present at the base of typical hog cholera ulcers, " and at 

 the same time (by the use of rabbits immunized against this species) the ap- 

 parent absence of virulent hog cholera bacilli [E. S. R., 22, p. 788]. In order 

 to learn something of the effects attributable to mixed infection and the in- 

 fluence of contagion (bacillar) in producing this condition, post-mortem exami- 

 nation and bacteriologic culture tests have been made as far as possible on all 

 material available during the past two years. This includes exjjerimentaUy 

 infected animals, pigs artificially infected for serum production, hogs con- 

 demned for cholera at the packing plant or city abattoir at Little Rock, and 

 material obtained from outbreaks of hog disease on farms in this State." The 

 material from the serum plant differed from that obtained from farm outbreaks 

 or experimental pens, since these animals (listed as "virus pigs") were often 

 killed several days before death would naturally have occurred; they were 

 also usually infected by strains of cholera virus of which no bacteriologic 

 study had been made. 



Out of 40 cases obtained from farm outbreaks, all with one possible exception 

 were hog cholera. B. suipestifer was found generally distributed in four 

 animals, although two of these showed no intestinal lesions. In the liver of 

 one animal B. coli was present and in another streptococci were found. In 

 three others unidentified nonfermenting bacilli representing three different 

 species were noted, and in three other animals cocci were present. Negative 

 results were obtained in 30 cases. A coccus morphologically resembling the 

 Micrococcus catarrhalis was obtained from the engorged spleen of a hog having 

 a marked bilateral pulmonary involvement. "Preparations from the lung 

 showed microscopically numerous organisms of varied species including small 

 bi-polar staining ovals." The animal culture tests for bacilli of the hog cholera 

 group were negative. 



Tests made in connection with these experiments showed the infrequency 

 with which bacilli of the hog-cholera type occur in the animals in natural out- 

 breaks of the disease as compared with those artificially infected. The disease 

 which now mostly prevails in Arkansas (termed " Winslow type") is not 

 accompanied by this mixed infection either in animals naturally infected or in 

 those inoculated from them. One experiment indicated that " a generalization 

 of B. suipestifer in the body of the animal greatly increases the severity of the 

 disease and aggravates the ante-mortem symptoms although producing no char- 

 acteristic post-mortem lesions. However, this mixed infection and increased 

 virulence was not transmitted by cohabitation." 



From the material obtained from the serum plant " it is shown that of 70 

 cases examined, B. suipestifer was found generalized in 21. Of these 16 had 

 been infected by inoculation (cholera infection), four by exposure, and one 

 without record. Of the animals furnishing the blood for inoculation bacterio- 

 logic data are on record for 21. It is seen that in the four cases in which B. 



