AIK, SOIL, AND WATER. 157 



Frankel's Borer. Frankel has devised a small apparatus in 

 the form of a borer, which contains near its lower end a small 

 cavity, which can be closed up by turning the handle, or opened 

 by turning in the opposite direction. 



It is introduced with the cavity closed, and when it is at the 

 desired depth, the handle is turned, the earth enters the cavity, 

 the handle again turned, incloses it completely, and the borer is 

 then withdrawn. 



The earth can then be mixed with the gelatine in a tube, and 

 this gelatine then rolled on the walls of the tube after the man- 

 ner of Esmarch, or it can be poured upon a glass plate, and the 

 colonies developed so. 



Another method is to wash the earth with sterilized water, 

 and the water then mixed with the gelatine, as many of the 

 gej:ms are taken up by the water. 



The roll-cultures of Esmarch give the best results, many of 

 the varieties usually found being anaerobic. 



Animals inoculated with the soil around Berlin die almost 

 always of malignant oedema, and with that of some other towns 

 invariably of tetanus. Many of the germs found are nitrogen 

 formers and play a great role in the economy of the soil. 



CONCLUSION. In tracing thus briefly the characteristics of 

 the more important bacteria, and the various methods used in 

 studying them, we are conscious of the very superficial manner 

 in which this has been done. We excuse ourselves, however, 

 on the ground that this work is but a wedge with which to enter 

 upon the study, or, for those who do not care to proceed further, 

 an eminence from which a fair view of the ground can be ob- 

 tained. In this, its humble mission, we trust it may meet with 

 success. 



