1 6 BACTERIA. 



Bienstock went so far as to describe a particular bacillus 

 which, he considered, was able by itself to produce the whole 

 series of changes that occur in the contents of the intestine 

 and in putrefying albumen or fibrine. This organism he 

 describes as being somewhat smaller than the Bacillus subtilis; 

 it is rod-shaped, but at one end there is usually a small 

 enlargement, in the centre of which a clear round spore 

 may be seen. It is from this feature that the organism 

 derives its name of "Drum-stick" bacillus. Cultivated on 

 fibrine it disintegrates it and gives rise to the formation of 

 leucine, tyrosine, carbonic acid, water, and ammonia, and 

 of traces of other putrefactive products. The process does 

 not however stop at this point ; the bacillus still continues 

 to act on the leucine and tyrosine, and decomposes them 

 into still simpler compounds ; whilst, if it be introduced 

 at once into a prepared solution of one of these earlier 

 decomposition products, tyrosine for example, it continues 

 the breaking-down process just as if it were still acting 

 on the tyrosine which had been formed during the process 

 of ordinary putrefaction. As De Bary points out, however, 

 this bacillus cannot claim a monopoly of the work connected 

 with putrefaction. If any putrefying fluid be examined, 

 countless organisms will be found, and amongst these very 

 different species may be observed. There are rods of different 

 sizes both as regards thickness and length, spirals of different 

 forms, micrococci of different sizes and arranged in different 

 groupings, one or other organism predominating according to 

 the nature of the putrefaction process, of the material that 

 is being broken down and the stage at which the breaking- 

 down process has arrived. It would appear in fact as 

 though there were developed special organisms for the setting 

 up of special fermentations, and also that after the breaking 

 down has been carried a certain length by one organism, the 

 aid of another is invoked to complete the process more 

 thoroughly and more expeditiously. We have in this, as in 

 the case of the process of digestion, an exemplification of 

 the fact that nature economizes her resources as much as 

 possible ; she does not call on the animal cells of the alimen- 

 tary tract to do work that can be equally well done by 

 micro-organisms, nor does she demand the exercise of more 

 than one or two functions from each of the simple proto- 

 plasmic specks that we call bacteria. To each one is assigned 



