282 



the biityric-acid fennenUitioii must be more completely excluded 

 than when using broth-bouillon or malt-wort. For although thelaller 

 liquids contain an excellent nitrogen food for B. poly my. r.n, they are 

 of less value for the butyric-acid ferments, for which the ammonium 

 salts are pi-eferable. Hence, in this case it is advisable to use a large 

 ËRi-ENMEiJEKflask, cis the great volume of soil which sinks to the 

 bottom as inoculation material, can then be better aerated, by which 

 butyric fermentation is prevented. 



Altliough the gi'owth is slow at the low temperature the liquid 

 becomes distinctly turbid and in most cases this is accompanied 

 with fermentation. This fernientation especially awakened our atten- 

 tion as we had expected an accumulation of B. megatkeriinn, which 

 causes no fermentation at all. 



As the Coli- and A'éro(ienesïe,vme\)\ix[\o\\^ had been prevented by 

 the previous heating, the butyric-acid and butylic fermentations by 

 the aeration, we now expected that the ïermewieiWon oï B. polyinyxa 

 was obtained, and this was confirmed by the pure culture. The 

 fermentation which is chiefly an alcoholic one, proves that our bacte- 

 rium belongs to the facultative (temporary) anaerobes, and the exa- 

 mination of the gas showed that it is almost pure carbonic acid. 



One of the most notable qualities of B. polymyxa is its secretion 

 of pectinase, i. e. the enzyme by which some microbes dissolve the 

 central laraellum of plant tissues, thereby disintegrating them into cells. 

 Hence, B. polyniyxa like B. mesentericus may under certain circum- 

 stances play a part in the retting of flax, although the real agent in 

 this case is the anaerobic B. pectinovorum. 



Beans, peas and other plant seeds, left to spontaneous corruption, 

 may change into rich cultures of B. polymyxa, the cell-walls of 

 cotyledons and of endosperm being easily attacked by pectinase, 

 whereby the interior of the seeds is changed to a pulpous mass ^). 

 For the preparation of a pure culture this method is less recom- 

 mendable than the two foregoing accumulations, on account of the 

 numerous hay bacteria which thereby simultaneously develop; it is, 

 however, a good way to get an i)iitial material for the said accu- 

 mulations themselves. 



It seems to us that the gejierality of B. polyniyxa in our surroun- 

 dings and particularly in the soil should be explained by its pectinase 

 secretion, which must give this species, in combination with its little 

 want of air, a great advantage over the other saprophytes. 



^) The enzyme seminase, which changes the endosperm of the Leguminosae 

 (Indigofera^ Ceratonia) into mannose, is perhaps identic with the pectinas of 

 B. polymyxa. 



