{ 329 ) 



Destined water J 00 

 K'^ HPO' 0,05 



NH^ CI 0,1 



Mg mV PO^ 0,05 



CaSO* 0,0i 



and inoculated with garden soil, sewage or canal water, of which 

 the two last cause the quickest growth. 



By the cock on the first tlask a measured quantity of oxyoen and 

 methan is admitted by means of a gas burette. The liquid is there- 

 by pressed into the other tlask, and when it has lowered until a 

 layer of about 1 cM. remains in the first flask, then the middle- 

 cock is shut and at last the admission-cock. 



The cultivation is effected at about 30° C. After a period, varyino- 

 from 2 — 4 days, a film is observed on the liquid, which rapidly 

 increases in thickness and then shows a distinct pink colour. Beneath 

 the film the liquid, clear at first, begins te display a considerable 

 turbidity caused by foreign microbes, which feed on the dead bac- 

 terial bodies of the floating film. Later on a great number of amoe- 

 bes and monads develop in the film and in the liquid, evidently at 

 the expense of tiie methan bacteriaj no other material for food being 

 present. In the other flask no film appears on the liquid. 



Transports to a same liquid in an apparatus like the former, easily 

 produce a new film, and, when garden soil is used for the infection, 

 it grows even faster than in the crude culture. 



An analysis of the gas after about a week, shows that the methan 

 has quite or partly disappeared whilst a considerable quantity of carbonic 

 acid is formed. The film is found chiefly to consist of bacteria be- 

 longing to one single species, which has proved to be the microbe 

 which makes the methan disappear. It is a short, rather thick 

 rodlet, immobile in the film, mobile or immobile in the plate cultures. 

 Always the individuals are united by a layer of slime. 



The length of this bacterium, which will provisorily be called 

 Bacillus metlianicus, is 4 — 5 ft, its thickness 2 — 3 ft. 



It is not yet ascertained whether this species has already been 

 found under other conditions of life and described elsewhere without 

 the knowledge of its relation to methan. The question whether there 

 exists only one or more than one species possessing the faculty to 

 live on methan is also subjected to further investigation. 



The methan bacterium is easily obtained in pure culture by cul- 

 tivation on w^ashed agar, containing the necessary salts, at a tem- 

 perature of circa 30^ C, in an atmosphere of V„ methan and Y, air, 



