14° BACTERIA. 



to 3/«, united in short chains, or curved rods. Con- 

 striction and division take place between the segments of 

 the chain as the process of vegetation goes on. A small 

 quantity of this mycoderma, which occurs as a wrinkled 

 membrane on the surface of liquids that are undergoing 

 acetic fermentation, is first sowed on the surface of an 

 aqueous liquid containing two per cent, of alcohol, one per 

 cent, of vinegar, and traces of alkaline and alkaline-earthy 

 phosphates. When the surface is covered with the mem- 

 brane the alcohol begins to acidify. This action being fully 

 set up, some alcohol, wine, or beer mixed with alcohol, is 

 each day added to the liquid, in small quantities ; this is 

 continued till the oxidation becomes slower ; the acetiiication 

 is then allowed to terminate, and the vinegar is drawn off. 

 The membrane is collected, washed, and employed for a new 

 operation. It is better always to give the plant sufficient 

 alcohol, so that its activity may not be exerted on the 

 acetic acid. Nor ought it "to remain too long out of the 

 liquid, or it would lose its active force ; finally, it is better 

 to moderate its development, to prevent burning oxidation." 

 These last few lines are of special interest, as they show how 

 markedly favourable conditions of nutrition, and the supply 

 of special materials on which the organisms may act, modify 

 the process set up by the acidifying organism ; just as certain 

 organisms will select glycerine or sugar from a peptone 

 gelatine medium before they begin to act on the gelatine itself, 

 so the mycoderma aceti, under certain conditions, confines its 

 attention entirely to the alcohol, converting it into acetic 

 acid and then leaving it ; whilst, as soon as the glycerine in 

 the one case and the alcohol in the other, are completely used 

 up, or as soon as the activity of the protoplasm becomes so 

 great that it cannot derive sufficient material from the one, 

 it immediately attacks the other, and continues the oxidizing 

 process. Not only so, but the various organisms appear to 

 be specialized at the different stages of the resolution of 

 organic matter ; each, during the stage at which it can 

 perform its share of the work, appearing not only to multiply 

 much more rapidly than the other organisms with which it 

 is found but actually holding them in check. In this 

 respect, the vegetable protoplasm of the lower organisms is 

 only like the protoplasm of the cells of the higher animal 

 organisms. In relation to pathogenic processes this is a 



