382 EXPERIMENT STATION EECOED. [Vol.38 



carriers. Only two observations were made in this work, however, and it is 

 indicated that no very definite conclusions can be drawn. 



Other results showed that putrefaction may destroy the cholera virus. It was 

 also shown that the usually accepted statement that hog cholera is invariably 

 transmitted by attendants is doubtful. 



In determining the period of infectivity of premises, it was found that in 

 no case did susceptible pigs contract the disease in infected pens 24 hours 

 after the removal of sick pigs. In one case the disease was contracted when 

 exposure took place 61 hours after the removal of sick pigs. In the concrete, 

 wooden, and sandy floored pens, pigs which were exposed 1 hour after the re- 

 moval of sick pigs contracted the disease, while in the pens which had sandy 

 loam and clay floors the pigs remained well. 



In determining the infectivity of excretions of cholera-infected hogs infec- 

 tious before symptoms appeared, it was found that the blood and urine were 

 both infectious on the first day after the injection of the hog, the feces on 

 the second day, and the eye and nose secretions on the third day. No visible 

 symptoms of the disease were observed until the fifth day, although there was a 

 slight increase in temperature on the fourth day. It thus appears that the 

 blood, urine, feces, and eye and nose secretions of cholera hogs may all be 

 infectious before the animal exhibits any symptoms of the disease. 



Increased virulence of the hog-cliolera bacillus produced by passage 

 through rabbits, C. Tenbkoeck {Jour. Expt. Med., 26 (1917), No. S, pp. 437- 

 440). — The author has increased the virulence of a culture of the hog-eholera 

 bacillus 1,000 times by passage through a series of 11 rabbits. A subcutaneous 

 injection of 20 organisms, or 0.00000001 cc. of a 24-hour bouillon culture, or a 

 drop of bouillon culture rubbed into the shaven skin produced a characteristic 

 disease in the rabbit resulting in death on or about the sixth day. 



The organism used in the work was isolated several years ago from the 

 spleen of a pig which died from hog cholera. After isolation the organism was 

 passed through a rabbit and has since been kept on slant agar in the cold, 

 transfers having been made monthly. It is a motile. Gram-negative rod, grow- 

 ing readily on the ordinary media and forming acid and gas in dextrose 

 bouillon but not attacking lactose or saccharose. It was quantitatively agglu- 

 tinated by serum from rabbits injected with other strains of the hog-cholera 

 bacillus, and when injected into animals caused the production of agglutinins 

 for other strains of the hog-cholera bacillus. 



The significance of agglutinins in the immunity of the rabbit to the hog- 

 cholera bacillus, G. Tenbroeck (Jour. Expt. Med., 26 {1917), No. S, pp. 44I- 

 45I). — The results of the work reported indicate that "rabbits may show a 

 high agglutination titer to the hog-cholera bacillus and have no immunity 

 and, on the other hand, immune animals may have a comparatively low aggluti- 

 nation titer." With the organism used it is considered that the height of the 

 agglutination titer does not indicate the degree of immunity. 



Because of the similarity, biologically and pathologically, between the 

 organism used in the work reported and the typhoid bacillus it is concluded 

 that the degree of agglutination titer in man does not indicate the actual degree 

 of immunity to the typhoid organism. The necessity of testing other organ- 

 isms before a more general conclusion can be drawn is noted. "This does not 

 mean that agglutinins are not related to immunity but it brings up the question 

 of the wisdom of using them as a guide in immunization with the colon-typhoid 

 group. When injected into the normal, vaccinated, or immune rabbit, the 

 virulent hog-cholera bacillus Is rapidly clumped and disappears from the circu- 

 lation. Forty minutes after injection these organisms can be found in 

 phagocytes in the liver." 



