m'TYRirrM AND HACILIJ-S BITYIUCCS 143 



by fusion ( Kig.4S) and the stopper smeared with warm paraffin. Ksmarch 

 roll cultures cm t .lieu be prepared. If plate cultures (e.y. in Petri dishes) are 

 to- be exposed to an inert gas, they are (according to P. LIBORIUS (I.) ) placed 

 under a bell (of copper, Arc.) which can be tightly fixed by screw clamps against a 

 caoutchouc plate. The gas (when hydrogen is used) enters through a tube fixed 

 in the crown of the bell, and leaves by way of another tube situated below. 



It is impossible to refrain from mentioning that there is another method 

 capable of taking rank with those described, and fulfilling all the conditions 

 usually prevailing during anaerobic growth in Nature, viz., the simultaneous 

 presence of strongly aerobic organisms. It is certain that anaerobic organisms 

 can often be detected in liquids to which air has unrestricted access, and sucli 

 associations of aerobic and anaerobic organisms are not difficult to bring about 

 by artificial means, this having been successfully attempted by R. PENZO (I.), 

 BEYERINCK (II.), and others. The application of this method is, however, 

 somewhat limited, since, of course, only mixed cultures can be produced by 

 its aid. 



It was remarked by Pasteur that the growth of anaerobic organisms could 

 be promoted by an addition of sugar to the nutrient medium. Now, an 

 alkaline solution of grape-sugar is well known to have a strongly reducing 

 action ; hence these two facts induced KITASATO arid WEYL (I.) to ascertain 

 whether other reducing bodies were equally efficient ; arid they strongly recom- 

 mended the addition of 0.3-0.5 per cent, of sodium formate, or of o.i per cent, 

 of sodium indigo-sulphate. A solid nutrient medium, qualified and stained blue 

 by the last-named substance, is decolorised as far as the growth of the reducing 

 organism extends. The use of indigo-sulphuric acid as a test for reducing 

 action was first practised in 1858 by M. TRAUBE (I.) in his researches on 

 ferments, and A. SPINA (I.) was the first to employ the sodium salt as a reagent 

 for the same purpose. 



115. Clostridium Butyricum (Prazmowski) and Bacillus 

 Butyrieus (Hueppe). 



Pasteur's discovery that organic life is possible without free oxygen, and that 

 certain organisms can obtain the energy they need by so breaking down organic 

 compounds as to liberate heat, is one of the highest importance for physiology 

 generally. The amount of heat so evolved is naturally much less than it would 

 be if the compounds in question were directly converted into carbon dioxide. 

 Pasteur, however, went somewhat too far in founding on this newly-discovered 

 fact a theory of fermentation which culminated in the assertion that : " Fermen- 

 tation is a universal phenomenon, and consists of life without air, life without 

 free oxygen," because, if this definition be accepted, we should be able to speak 

 or' but few phenomena as fermentation, and, in particular, it would be necessary 

 to discontinue the application of the term to those decomposition processes 

 that from time immemorial have been, and are even now, principally borne in 

 mind in speaking of "fermentation," viz., the alcoholic fermentation excited by 

 yeast, an operation which proceeds both with and without free oxygen. 



To return to the " vibrion butyrique." In the years 1877 to 1880, A. 

 PRAZMOWSKI (I.) published a careful morphological investigation of a butyric 

 acid bacterium, presumably identical with the vibrion butyrique though this 

 cannot be stated with certainty. Elevating the designation Clostridium (first 

 used by Trecul, and then only to indicate a form of growth) to a generic term, 

 Prazmowski named two new species of bacteria Clostridium butyricum and 

 Clostridium Polymyxa. The latter completely coincides with the former both in 

 morphology and life history, but differs from the strictly anaerobic Cl. butyricum 



