ZOOLOGY AXD BOTANY, MICROSCOPY, ETC. 399 



varying conditions. The bacillus could not be isolated from eighteen 

 samples of desiccated dust obtained from " vacuum cleaners," but viru- 

 lent bacilli were obtained in three samples out of eighteen of fresh dust. 

 Two of these positive samples were obtained from scrapings from the 

 floors of omnibuses, doubtless contaminated by expectorations. 



An attempt was made to simulate the conditions met with in apart- 

 ments, in order to see what influence, if any. such surroundings had on 

 the virulence of the bacillus. Tubercle bacilli were mixed with sterile 

 powdered dust and placed in a shallow layer in the bottom of a Petri 

 dish, and then exposed to diffuse light. The bacilli retained their viru- 

 lence for about eight months, and when the virulence was declining, 

 and could only cause a slow tuberculosis in guinea-pigs, virulent bacilli 

 could still be obtained from the lesions of such animals. 



Attenuated tubercle bacilli are met with in lupus, but the origin of 

 these strains k uncertain. They probably exist in nature, but have not 

 yet been isolated. Bacilli attenuated for the guinea-pig are not exalted 

 by passage through these animals, though the virulence for the guinea- 

 pig is raised by passage through monkeys (Rhesus cyaocephalus). 

 X-ray application does not appear to affect the virulence of organisms 

 inoculated subcutaneously into guinea-pigs. The bacilli cultivated at 

 the end of the irradiation showed the same virulence as the organisms 

 used for inoculating. 



'- ■ 



The Resistance of Fowl to Infection with Spirocheta gallin- 

 arum.* — It having been observed that hypertrophy of the thyroid gland 

 and spleen are constantly met with in the course of fowl spirochetosis, 

 L. Launoy and M. Levy-Bruhl have investigated the role played by 

 these organs in infection of the fowl by Spirochaeta gallinarum. The 

 preliminary removal of the thyroid gland and spleen does not affect the 

 resistance of the adult fowl to spirochetal infection nor the production 

 of a state of immunity. In cases where the spleen has been removed, the 

 septicemia resulting from infection of the animal is much greater than 

 in the case of a control fowl in which the spleen has not been removed, 

 but, on the other hand, the clinical symptoms of the disease are much 

 less marked and the phenomena of intoxication are almost absent. 

 This apparently paradoxical result is probably due to the fact that 

 normally ti considerable number of spirochetes are destroyed in the 

 spleen, and that massive doses of toxic substances are thus liberated, 

 such toxins being responsible for the "andynamic syndrome" so 

 characteristic of infection by the organism in question. 



Studies on Bacillus oedematis maligni and Bacillus chauvei.j — 

 M. Nicolle, E. Cesari and Mile. A. Raphael have conducted a Beries of 

 experiments with Bacillus adematis maligni and Bacillus chauvsei which 

 tend to show that the biochemical reactions of the two organisms are 

 identical. The effects of the soluble toxin, in each case, on guinea-] 

 and rabbits, by intravenous or subcutaneous injection, are identical, and 



* Ann. Inst. Pasteur, xxix. (1915) pp. 213-20. 

 t Ann. Iu-t. Pasteur, xxix. (1915) pp. 165 -77 



