§ IX. J Decomposition of proteid. 103 



Vandevelde's observation (49) that B. subtilis certainly gives 

 rise to slight fermentation in meat-extract, glycerine, and grape- 

 sugar, after the ox3'gen is consumed, with special production of 

 butyric acid, can hardly be taken into consideration, for he 

 speaks of very small amounts produced from fermentation, 

 while Fitz states that the amount of butyric acid produced is 

 very large. 



In the absence of more precise morphological observations, 

 the species of the Bacillus subtilis of Fitz's starch-fermentation 

 must for the present remain undetermined. In connection with 

 this question I will here briefly repeat the remark made on 

 page 74, that there are certainly several saprophytic and endo- 

 sporous species of Bacteria, which are very like Bacillus subtilis, 

 and have no doubt been frequently confounded with it. Nothing 

 certain can at present be stated with regard to their effects as 

 ferments. The B. subtilis of Brefeld and Prazmowski, the only 

 form to which I give the name, is clearly distinguished from 

 them by the assemblage of characters described in former lec- 

 tures, and by the mode of germination (page z i ), as well as by 

 their collecting on the surface of the nutrient fluid into 

 membranes which are folded in wrinkles, and consist of 

 filaments disposed in parallel zigzags and ultimately forming 

 spores, and by the ellipsoid comparatively broad spores them- 

 selves. 



8. If we examine in conclusion the decompositions which occur 

 in proteid compounds and in glue, we shall first of all see no 

 reason to doubt that all of them, and especially those which are 

 accompanied by the development of gas and are usually known 

 as processes of putrefaction, are the work of Bacteria. The 

 data which we possess show that the processes in these decom- 

 positions and the participation of the different species of Bac- 

 teria in them are, as might be expected, extremely multifarious. 

 The work of distinguishing between the species of Bacteria con- 

 cerned and their specific modes of operation is still in its 

 infancy. 



