88 EXPERIMENT STATION RECORD. 



of the disease studied by the authors. The exact role played by this organism, 



however, is not definitely known. 



It appears to be necessary to assume that hogs are subject to a disease caused by 

 the hog cholera bacillus and having no connection with that produced by the filter- 

 able virus found in the outbreaks of the hog disease under discussion. Whatever 

 may be the influences which lead to an invasion of healthy hogs by the hog cholera 

 bacillus the authors believe that the filterable virus investigated by them is the 

 direct cause of the high degree of infectiousness characteristic of the disea'se which 

 was studied. 



The virulence of cultures of bacilli of swine erysipelas after the addition 

 of serum or grape sugar, P. Gobdan (Berlin. Tierarztl. Wchnschr., 1904, No. 53, 

 pp. 891, 892). — A considerable series of culture experiments along this line were car- 

 ried out by the author. It was not possible to immunize mice against swine erysipe- 

 las by inoculation with erysipelas bacilli to which grape sugar had been added. By 

 the addition of 0.1 per cent sheep-blood serum to the nutrient bouillon it was possi- 

 ble to increase the reproductive power of the bacilli. It was noticed that even 

 after 6 weeks such cultures had not lost their virulence as they usually do in ordinary 

 media. 



Combating fowl cholera and swine plague, Klett and Braun (Dent. Tierarztl. 

 Wchnschr., 12 {1904), Nos. 51, pp. 517-521; 52, pp. 529-532; 53, pp. 545-547).— In 

 the opinion of the authors the toxins in filtrates and the endotoxins of Bacillus 

 aviseptlcus and B. suisepticus are identical. The former produces more toxin than the 

 latter. The toxicity of the toxins from both organisms appears to be independent 

 of the virulence. 



For the purpose of producing a preventive serum against swine plague, horses 

 were treated, for long periods, with dead cultures and with filtrates. The serum 

 thus obtained was both bactericidal and antitoxic. The passive immunity produced 

 by treatment of gray mice with this serum lasted for 3 or 4 weeks. It was not deter- 

 mined whether an active immunity could be brought about by this serum. Brief 

 notes are also given on hog cholera. 



Bacterial pyelonephritis in hogs, E. Wyssmann (Schweiz. Arch. Tierheilk., 46 

 (1904), No. 6, pp. 287-290). — The symptoms and etiology of this disease are briefly 

 discussed. In some cases studied by the author it is believed that the disease was 

 due to a mixed infection which occurred at the time of birth. The lesions caused 

 during the development of this disease are briefly described. 



The external parasites of hogs, E. C. Stevenson ( U. S. Dept. Agr., Bar. Anim. 

 Indus. Bui. H9, [>}>. 44, figs. 29) . — The most important external parasites of the hog 

 are Hsematopinus mis, Sarcoptes scabiei mis, and the mite which causes follicular 

 mange. The last named parasite, however, seemed to be' of little economic 

 importance. 



A historic review is given of the appearance, synonymy, and classification of IT. 

 mis. This parasite lives on domesticated and wild hogs, but is not known to live as 

 a parasite on any other animal. The insect is described in detail in all of its stages. 

 The eggs are deposited largely on the hair back of the ears and along the shoulders 

 and flanks. The period of incubation appears to be 15 or 16 days at a temperature 

 of 85° F. The parasites cause an irritation of the skin with the formation of scales 

 and inflammation. Certain authors believe that hog lice may carry the infection of 

 hog cholera. 



In combating this pest the pens of infested hogs should be thoroughly treated. 

 If they are kept vacant for 2 weeks or more the lice seem to perish. Various reme- 

 dies have been suggested for the treatment of infested buildings, but whitewash made 

 in the proportion of H lbs. of lime to 1 gal. of water is probably the. most conven- 

 ient method. Experiments with remedies applied directly to hogs, such as kerosene 

 emulsion, kerosene and water, pure kerosene, and benzine emulsion are successful, 



