(23) 



lation of the mobile microbes, which are more attracted by the food 

 than by the oxygen, not in the meniscus and at the edge of the 

 preparation, but at some distance. I observed this in an aerobic 

 species, which I have called Bacillus perlibratus^ where trophotaxis 

 may become so strong, that microaërophily is mimicked, and was 

 erroneously described by me as such ^). 



With abundant food, however, nothing is to be seen of these 

 phenomena, so that by attentive observation microaërophily may 

 always distinctly be recognised. 



I now return <o the anaerobes of the putrefaction of proteids, 

 and in particular to the second important form, the skatolbactery. 

 Of this polymorphous form I examined, as already said, material 

 closely allied to the tetanus-bacillus, which material is strictly 

 anaerobic, and perhaps ought to be considered as the most character- 

 istic for the process of putrefaction in general. I isolated various 

 varieties and by means of growth experiments I was enabled to state 

 microaërophily. The mobility of my varieties was too insignificant 

 to be of use for the production of figures of respiration. "When using 

 the above mentioned pepton gelatine as nutrient matter and Saccha- 

 rowyces apicidatus for the absorption of oxygen, most convincing 

 „niveaus", of a light brown color and with much growth, originate 

 in deep experiment-tubes at a certain distance from the surface, 

 in the surface itself the transparent clear colonies of the apicu- 

 latus-yeast develop vigorously, the skatolbacteria not being able to 

 develop there. 



Tiie spore-formation seems here also to be favored by a small 

 quantity of oxygen. Certain it is that spores are the most profusely 

 formed in the niveau, and as their production goes parallel, first 

 to the weakening and then to the complete liquefying of the gela- 

 tine, it is clear that also the latter process must begin in the 

 niveau, to become only much later perceptible in the depth, and 

 without reaching the surface at all. 



I wish to terminate this survey of the obligatous anaërobics, 

 studied by me, with the statement that the existence of micro- 

 aërophily could also be proved for Spirillum desulfuricans by means 

 of growth experiments. 



This species is, in opposition to 6'. tenue, strictly anaerobic and 

 belongs morphologically to quite another group than the butyric- 

 ferments and the bacteria of putrefaction, which is clearly demon- 



1) Centralblatt fur Bacteriologie, Bd. U, pag. 839, 1893. 



