144 BUTYRIC ACID FERMENTATION 



both by its inability to exist in the absence of oxygen, and also by its incapacity 

 to incite fermentation (in the restricted sense of the term). Fig. 49 reproduces 

 the vegetative forms of growth depicted by Prazmowski as those ot his butyric 

 acid bacterium. They are mostly plump rods, some i /* broad. The generation 

 period was determined by Prazmowski as about thirty to thirty-five minutes at 

 35 C., and forty-five to fifty minutes at 30 0. Under certain conditions, and 

 especially whilst young, the rods store up in their plasma a substance which 

 resembles starch (amylum) in being stained blue by iodine. This phenomenon 

 had already been noticed by Trecul, who gave it expression in the generic name 

 of Amylobacter, which he applied to these Schizomycetes. During the formation 

 of spores the rods swell up, as related and shown in 49. The power of with- 

 standing heat possessed by the endospores of Cl. butyricum was examined by 

 Prazmowski. They are able to remain in boiling water for five minutes without 

 injury ; but if the treatment be prolonged to twice that duration, then only the 



FIG. 49. Clostridiuin butyricum. 

 Vegetative forms of growth ; short rods of 

 different lengths, partly straight (c, d), 

 partly curved (a, b). Magn. 1020. {After 

 Prazmowski.) 



FIG. 50. 



Clostridiuin butyricitin. 

 With endospore. 



Stained cilia. Magn. 2000. 

 (After A. Fischer.) 



hardiest spores of all are left alive, and even these succumb if the boiling be 

 extended to fifteen minutes. The progress of the germination of the endospores 

 has already been described in 57 (q.v.\ The brisk locomotion of the rods is 

 produced by a large number of cilia, shown in Fig. 50. Prazmowski did not 

 have pure cultures, in the present acceptance of the term, at disposal for his 

 researches, but was obliged to confine himself to an approximately pure culture 

 prepared by means of Roberts' boiling method ( 107). The same remark 

 applies to a valuable treatise by A. FITZ (VII.), wherein the fermentative 

 activity of a fission fungus named Bacillus butylicus is reported upon. 



After E. Ch. Hansen, in 1878-79, had established, in connection with acetic 

 fermentation, the new and important fact that this decomposition process is 

 effected by at least two different species of bacteria, F. HUEPPE (IV.) in 1884 

 found the same to be the case with butyric fermentation, and discovered a 

 Bacillus butyricus which exerted its decomposing activity in presence of air. 

 This fact was confirmed by MAX GRUBEB (II.), working with a reliable method 

 of pure culture in 1887, and it was at the same time demonstrated that the 

 Clostridiuin butyricum of Prazmowski consists of a number of closely allied, but 

 nevertheless distinct, species. Nearly related to this is a ferment isolated by 

 P. LIBORIUS (I.) from old cheese, and introduced into literature under the name 

 of Ciostridium ftetidum. This organism liberates very foul-smelling gases, in 



