On the relation of the obligatous anaërobics 



to free oxygen. 



Proceedings of the Section of Sciences, Kon. Akademie van Wetenschappen, Amster- 

 dam, Vol. I, 1898, p. 14—26. — Verscheen onder den titel »Over zuurstofbehoefte bij 

 obligaatanaëroben» in Verslagen Kon. Akademie van Wetenschappen, Wis-en Natuurk. 

 Afd., Amsterdam, Deel VII, 1898, blz. 19-32, en ond-r den titel «Les organismes 

 anaérobies obligatoires ont-ils besoin d'oxygène libre?« in Archives Néerlandaises des 

 Sciences Exactes et Naturelles, Haarlem, Série II, Tomé II, 1899, p. 397—411. 



The relation of the living cell to free oxygen is best to be judged from the influ- 

 ence of this gas on the groivth and on the mobility. Of course, only the first 

 jnethod is of universal application. 



As to the mobile microbes, some time ago I gave the name of »figures of res- 

 piration« ') to the peculiar groupings, which originate in preparations destined for the 

 microscope, in consequence of the access of oxygen only along the edge of the examined 

 drop under the cover-glass, the microbes being thereby enabled to seek that quantity 

 of oxygen which is best adapted to their respiration. Three types may here be 

 distinguished according as the microbes seek the highest tension of the oxygen along 

 the edge, a middle tension at some distance of it, or the smallest tension in the centre 

 of the preparation. These types I called the aerobic, the spirillous and the anaëro- 

 bic type. 



Further experience has shown that the anaërobic type, characterised by the accumu- 

 lation of the moving microbes at that spot of the preparatitm where the oxygen tension 

 is minimum, — commonly near the centre, — does not exist as a special type, but 

 becomes visible only itnder particular circumstances, and further, that when the 

 aëration of the preparation is sufïiciently small, all anaërobics, examined till now, 

 appear to belong to the spirillous type, that is to say, they not only don't fly those 

 places in the preparation, where a small oxygen tension still exists, but they even 

 seek them. 



This tension, beneficient for the anaërobics is however very slight, whence follows, 

 that by using only a moderate number of microbes, consuming but very little oxygen, 

 there may enter at the edge more oxygen than is wanted. In such a case the tension, 

 most approaching the required optimum, will be found in the centre. The accumu- 

 lation of the microbes will then also be localised to the centre, causing the semblance 

 of an anaërobic type as a special case. It is clear, that if this is the right expli- 

 cation, the true representatives of the second type, viz. the spirilli, must under cer- 



') Centralblatt für Bacteriologie, Bd. 14, pag. 837, 1893- 



