K. F. MEYER 6ii 



O'Brien,^ and Trawinski.* I identified fourteen strains of a series of fifty-eight as B. enteriti- 

 dis and isolated, just as Krumwiede and his associates did, both the B. entcritidis and B. 

 acrtryckc types from the animals of the same epidemic. By means of reciprocal absorption 

 tests a definite identification may be accomplished, and one may therefore conclude that the 

 causative organisms encountered in the natural infections are mostly strains which are either 

 closely related to the B. acrtryckc or the B. entcritidis group. 



Experimental septicemic infections can be produced in guinea pigs, mice, rats, 

 rabbits, and pigeons (Eckersdorfif)^ by subcutaneous and intraperitoneal injections of 

 relatively few organisms (aertrycke type) of recently isolated epidemic strains. The 

 virulence may be preserved in desiccated spleens (Schoenholz)^ since it decreases 

 rapidly on agar (Bainbridge and O'Brien). Uchida^ concluded from a series of experi- 

 ments that the peritoneum possesses a greater susceptibility for the infection than 

 the blood-vessel system. Some of the guinea pigs injected intraperitoneally with one 

 to ten organisms died in from two to three days; the same strain did not infect regu- 

 larly by the subcutaneous route. The majority of workers who attempted to infect 

 guinea pigs per os record absolutely negative or inconclusive results (Dieterlen,'' 

 Howell and Schultz,^ Okamoto/ Freund,' Uchida,™ and others). An active disease 

 with a high mortality may be secured in a "clean stock" in rare and irregular instances 

 when enormous numbers of bacteria (60 cc. of broth culture or one-tenth of a Blake 

 flask) are fed repeatedly. Some unpublished observations indicate that the infective 

 dose may be decreased provided the virulence has been exalted by repeated and rapid 

 passage through animals or by continuous cultivation in a special medium. Ordi- 

 narily the ingested bacilli persist in the digestive tube (Shaw, Weiner, and Meyer, un- 

 published observations); fecal excretion may continue for three to four weeks, and 

 at autopsy the organisms may be found in the spleen (Smith and Nelson), mesenteric 

 lymph nodes and the bile (Shaw and Meyer). Occasionally cultures can be secured 

 which are rapidly invasive on intracutaneous injection (Averill and Meyer, unpub- 

 lished observations). The entcritidis strains tested by the writer behaved on guinea 

 pigs like the aertrycke cultures. A very important fact is quite often overlooked. Al- 

 though the causative organisms are discharged in the excreta and have been found 

 by Freund on the hay or the carrots (six times in ten tests) in the cages of the diseased 

 or the dead animals, fatal contact infections are very rarely observed (Petrie and 

 O'Brien, O'Brien, Bainbridge and O'Brien, Freund, Okamoto, Meyer, and others) 

 when healthy guinea pigs are thus exposed to the virus. On the other hand, mice in- 

 fected with paratyphoid strains of guinea pig origin as a rule spread a rapidly fatal 

 disease among the healthy contacts. In the light of these observations Petrie and 

 O'Brien considered the aertrycke organism merely a secondary invader to a "filter 



I Bainbridge, F. A., and O'Brien, R. A.: toe. cit. 



^Trawinski, A.: loc. cit. 



3 Eckersdorff, O.: loc. cit. 



•^ Schoenholz, P.: unpublished observations. 



5 Uchida, Y. : Ztschr.f. Ilyg. u. Infektionskrankh., 106, 297. 1926. 



•"Dieterlen, T.: toe. cit. 



"Howell, K. M., and Schultz, O. T.: toe. eit. » Freund, R.: loc. cit. 



* Okamoto, T.: loc. cit. '» Uchida, Y.: loc. cit. 



