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mostly enclosed in the somewhat swollen ends of the staves, and 

 surrounded by a hollow space. Though this bacillus is evidently 

 polarically constructed, it moves spore-end or tail-end forward, 

 and may suddenly change the direction of the movement. When a 

 little air accedes, the staves may grow out into long threads and 

 the motion ceases. 



With a total withdrawal of oxygen there is a disposition for the 

 formation of Clostridia, but without a marked difference between 

 an „oxygenform" and a „clostridiumform" as found in Gramtlo- 

 bader butijlicum. 



If the nutrient matter is merely albumen or pepton, gases are pro- 

 duced, whose quantity increases more or less by the addition of glucose. 



Fibrine and proteids produce volatile sulphides, sometimes in great 

 profusion ; production of merkaptan, too, is observed under unknown 

 circumstances. The colonies liquefy ihe gelatine of the above com- 

 position; their surface is quite characteristically pointed, evidently 

 because many small shoots pierce slightly into the gelatine, before 

 the melting sets in. This may be compared with the behaviour of 

 anthrax, where, however, there is no melting at all. Commonly 

 whether spores or vegetative cells are sown out, only few germs 

 develop, which proves, that the nutrient matter itself, — even the 

 best I could procure, — acts in a high degree as a „bactericid" in 

 relation to B. sept kus. The growth is slow, even at brooding tem- 

 perature, when compared to allied aerobics. 



Concerning the necessity of oxygen for B. septicus and the skatol- 

 bactery, I could state what follows. 



B. septicus I observed as well with regard to the figures of 

 respiration, as to the growth. In both ways the microai-rophily 

 could with certainty be stated. As this bacillus is extremely mobile, 

 and as the spores render the swarms of bacteria very opaque, the 

 study of the figures of respiration offers no difficulty. 



A small number of bacteria accumulating in the centre of the 

 preparation, produce the impression of aërophoby. If on the con- 

 trary, the bacteria are very numerous, a circular accumulation 

 is formed at some distance from the edge of the cover-glass and 

 the meniskus, pointing out the place where the tension of oxygen 

 is optimum. If we examine the inner field, i. e. the part surrounded 

 by the accumulation and totally deprived of oxygen, there, too, all 

 is in motion. This morion is however much slower, more staggering 

 and uncertain, than in the accumulation itself. I think that this 

 innei- part is continually supplied w^ith individuals from the accu- 

 mulation, which individuals, after some time return to the latter, to 



