392 BACTERIOLOGY. 



there is little tendency for the daughter cells to adhere 

 together or to form chains. In cultures they are com- 

 monly massed together, by a gelatinous material, in the 

 form of zoogloea They do not form spores, and are 

 probably not motile, though Winogradsky believes he 

 has occasionally detected them in active motion. As 

 has been stated, they do not grow upon the ordinary 

 nutrient media, and cannot, therefore, be isolated by 

 the means commonly employed in separating different 

 species of bacteria. The most astonishing property of 

 this organism is its ability to grow and perform its spe- 

 cific fermentative function in solution absolutely devoid 

 of organic matter. It is believed to be able to obtain 

 its necessary carbon from carbonic acid. For its isola- 

 tion and cultivation Winogradsky recommends the fol- 

 lowing solution : 



Ammonium sulphate 1 gramme. 



Potassium phosphate 1 " 



Pure water 1000 c.c. 



To each flask containing 100 c.c. of this fluid is added 

 from 0.5 to 1.0 gramme of basic magnesium carbonate 

 suspended in a little distilled water and sterilized by 

 boiling. One of the flasks is then to be inoculated with 

 a minute portion of the soil under investigation, and 

 after four to five days a small portion is to be withdrawn 

 by means of a capillary pipette from over the surface 

 of the layer of magnesium carbonate and transferred to 

 a second flask, and similarly after four or five days from 

 this to a third flask, and so on. As this medium does 

 not offer conditions favorable to the growth of bacteria 

 requiring organic matter for their development, those 

 that were originally introduced with the soil quickly 

 disappear, and ultimately only the nitrifying organisms 



