568 SUMMARY OF CURRENT RESEARCHES RELATING TO 



characters predominated, in the latter anaerobic. The sulphuretted 

 hydrogen was detected by means of slips of filter-paper soaked in a 

 solution of alkaline acetate of lead. 



The first series of experiments were made with eggs ; the white and 

 yolk being used, both raw and cooked. HgS was produced under all 

 circumstances, but in varying quantities. Besides eggs, blood-serum 

 and peptonized bouillon were employed, also with production of HgS. 

 In milk and sterilized casein no gas was developed. Hence the author 

 infers that the cultivation medium seems to exert the decisive action, 

 and not the presence or absence of oxygen. 



Experiments with sterilized urine showed that JB. sulpJiureum pro- 

 duced HgS, but Proteus sulphureus failed to do so. 



The addition of 0*5-3 per cent, of grape and milk sugars to pep- 

 tonized broth prevented the formation of HgS ; hence the same microbe 

 can effect a putrefaction which, according to the nature of the cultivation- 

 medium, is with or without odour. 



Experiments with certain sulphur salts, as sulphates and snlpho- 

 cyanates, failed, but positive results were obtained from a • 5 per cent, 

 solution of hyposulphate of soda in the presence of air, with Proteus 

 sulphureus ; while B. sulphureum could only do so in the absence of air. 



The last series of experiments were devoted to testing the assertion 

 of Duclaux that the so-called aerobic fermentations are truly anaerobic. 

 Three flasks of bouillon were taken ; in one the surface was covered 

 with oil, in the second the neck was merely plugged with cotton-wool, 

 in the third arrangements were made to aerate the bouillon during the 

 experiment. From the results of these experiments the author con- 

 cludes that aerobiosis and anaerobiosis do not count for everything, but 

 that the ultimate causes are to be sought for in the specific qualities of 

 protoplasm. 



Bacilliis of Leprosy.* — Dr. C. Q. Jackson finds that the micro- 

 scopical character and general morphology of Bacillus leprae greatly 

 resemble B. tuberculosis, but a point of difference is to be noted in that 

 the bacilli of tubercle are not motile, while some of those of leprosy are. 

 Inoculation with B. tuberculosis readily produces a characteristic 

 definitely tubercular lesion, but the Bacillus of leprosy is difficult to 

 inoculate in the lower animals, and in Man appears to require a certain 

 predisposing condition. B. leprse stains more easily than B. tuberculosis, 

 though the same staining processes and reactions are applicable to both. 



Vaccinal Properties of Microbes, j — M. A. Chauveau has, since 

 1884, been engaged in cultivating successive generations of Bacillus 

 anthracis under a pressure of about nine atmospheres. He has thus 

 succeeded in diminishing considerably its virulence, and in making it 

 harmless to the sheep. Taking two infusions, one of which (A) was 

 rather less powerful than the other (B), M. Chauveau has found that 

 the first generation of A, after cultivation in compressed oxygen, was 

 completely devoid of any pathogenic power ; and successive generations, 

 cultivated under normal conditions, gave also innocuous microbes. B 

 had to be submitted for two generations to the increased pressure of 

 oxygen before it lost its pathogenic powers. 



In neither case, however, was there any change in the form of the 



* Proc. Amer. Soc. Micr., x. (1888) pp. 119-27. 



t Comptes Rendus, cviii. (1889) pp. 319-24, 379-85. 



