STUDIES ON FERMENTATIOX. 291 



captured them from inability to escape, precisely in con- 

 sequence of that state of entanglement which they combined to 

 form, during the period of their active development. Besides 

 these we observed vibrios of the same diameter, but of much 

 smaller length, whirling round with great rapidity, and darting 

 backwards and forwards ; these were probably identical with the 

 longer ones, and possessed greater freedom of movement, no 

 doubt in consequence of their greater shortness. Not one of 

 these vibrios could be found throughout the mass of the liquid. 



We may remark that as there was a somewhat putrid odour 

 from the deposit in which the vibrios swarmed, the action must 

 have been one of reduction, and no doubt to this fact was due 

 the greyish coloration of the deposit. We suppose that the 

 substances employed, however pure, always contain some trace 

 of iron, which becomes converted into the sulphide, the black 

 colour of which would modify the originally white deposit of 

 insoluble tartrate and phosphate. 



But what is the nature of these vibrios ? We have already 

 said that we believe that they are nothing but the ordinary 

 vibrios of putrefaction, reduced to a state of extreme tenuity by 

 the special conditions of nutrition involved in the fermentable 

 medium used ; in a word, we think that the fermentation in 

 question might be called putrefaction of tartrate of lime. It 

 would be easy enough to determine this point by growing the 

 vibrios of such a fermentation in media adapted to the pro- 

 duction of the ordinary forms of vibrio ; but this is an experi- 

 ment which we have not ourselves tried. 



One word more on the subject of these curious beings. In a 

 great many of them there appears to be something like a clear 

 spot, a kind of bead, at one of their extremities. This is an 

 illusion arising from the fact that the extremity of these vibrios 

 is curved, hanging downwards, thus causing a greater refraction 

 at that particular point, and leading us to think that the 

 diameter is greater at that extremity. We may easily un- 

 deceive ourselves if we watch the movements of the vibrio, 

 when we will readily recognize the bend, especially as it is 



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