136 SUMMARY OF CURRENT RESEARCHES RELATING TO 



bacillus of swine-fever, and they found it fatal to mice, rabbits and pigeons, 

 but not to white or wild rats, dogs, or fowls. 



Necessity of Oxygen for Bacteria.* — Dr. P. Liborius publishes the 

 results of a series of experiments on the degree to which various bacteria 

 can carry on their vital functions under partial or entire exclusion of 

 oxygen. Of a variety of methods employed for excluding oxygen, the most 

 efficacious was found to be the replacement of the air by aqueous vapour 

 or by hydrogen ; almost as good results were obtained by the super- 

 position of a thickness of 3 cm. of a solid nutrient substance. The nutrient 

 employed was extract of meat peptone-gelatin with 5, 7, or 10 per cent, of 

 gelatin, and 1 per cent, of agar-agar. 



Some bacteria were found to be very indifferent to the exclusion of 

 oxygen ; these were especially Bacillus acidi ladici, Proteus vulgaris, Strep- 

 tococcus pyogenes, Bacillus pneumonise, B. crassus sputigenus, B. prodigiosus, 

 and B. murisepticus. Tlie growth of Staphylococcus aureus, B. typhoidei- 

 ahdominalis. Spirillum cholerse-asiaticse, S. tyrogenum, and S. Finhleri was 

 also not completely arrested by deprivation of oxygen. Other species 

 showed under these circumstances a change in their biological properties, a 

 loss of some characteristics, or an arrest of growth. But the degree of 

 deprivation of oxygen necessary for these changes varies with the different 

 species. 



The property first affected is the production of pigment, for which con- 

 tact with free oxygen is necessary. It follows that the bacteria can produce 

 only a chromogenous substance which is converted into a pigment by 

 oxidation. The power of peptonizing is also soon affected ; but this varies, 

 even when the supply of oxygen is abundant, according as the nutrient sub- 

 stance contains sugar or not. With the cholera-spirillum deliquescence is 

 prevented by the entire elimination of oxygen ; while with Bacillus pro- 

 digiosus and Proteus vidgaris it is only retarded under these circumstances. 

 The fermenting power of bacteria also depends largely on the composition 

 of the nutrient substance. Bacillus aerophilus appears to be the species 

 most dependent for its development on the presence of oxygen. 



A number of anaerobes were isolated by cultivation on solid substrata, 

 and the following specially described : — 1. Bacillus oedematis-maligni ; 

 bacilli 3/x long, 1 jx broad, often growing into long threads; spores not in 

 threads, but in single fusiform bacilli. 2. Clostridium fcetidum ; bacilli 1 /u, 

 broad, varying in length, actively motile, often in pseudo-filaments ; spores 

 usually in the middle of the swollen filament, but also towards the ends, 

 oval, strongly refractive. 3. Bacillus polypiformis ; bacilli slender, more 

 than 1 fj. broad, varying in length, with no tendency to the formation of 

 threads; spores oval or cylindrical, often occupying one-half to one-third 

 of the filament. 4. B. muscoides ; bacilli slowly motile, with slight ten- 

 dency to the formation of threads ; spores roundish oval, mostly terminal, 

 strongly refractive, 5. The pseudo-cedem bacilli ; found in company with 

 the (xdem-bacilli, thicker than they, surrounded by a light border, usually 

 with two spores in each bacillus. They are pathogenic, apparently in 

 consequence of the formation of a ptomaine. 



Bacteria in Drinking-water. f — Herr M. Bolton finds that certain bac- 

 teria exist in ordinary spring water, and are capable of multiplication in 

 it. Among these two may be specially mentioned : Micrococcus aquatilis, 

 which occurs as cocci collected into small irregular heaps, and Bacillus 



* Zeitschr. f. Hygiene, i. (1886) pp. 115-77 (2 pis.). See Bot. Centralbl., xxvii. 

 (1S86) p. 198. 



t Zcitsclir. f. Hygiene, i. (1886) pp. 76-114. [See Bot. Centralbl., xxyiii. (1886) p. 16. 



