1892.] MICROSCOPICAL JOURNAL. 245 



which portion serves as a handle. The segmental portion is 

 sharpened upon its convex surface. 



When it is desired to make a potato preparation, both ends of 

 a hirge potato are cut oft", and the plugger is passed through it by 

 a rotary vertical movement. The potato cylmder, which appears 

 in the plugger. should be long enough to reach a short distance 

 into the hollow handle, so that it will be held firmly. By pass- 

 ing the curved knife into the potato cylinder and across its diame- 

 ter in contact with the sides of the opening in the plugger, the 

 C3dinder is divided. The outer piece of the divided cylinder will 

 fall out, and the piece which remains in the phigger now has a 

 beveled surface for inoculation, and it can be removed by pushing 

 it up a short distance into the hollow handle of the plugger. 



The thin end of the section should be trimmed off for the dis- 

 tance of about half an inch to prevent its curling, and a notch 

 should be made in the side of the end of the cylindrical portion of 

 the section to admit the passage of moisture from the water res- 

 ervoir of the culture-tube to the potato chamber above it. 



Figure 3 represents the potato section placed in a reservoir-tube 

 ready for use. 



BACTERIOLOGY. 



What Has Been Done in Bacteriology in Relation to 

 Hygiene.* 



Bacteriology is a new science {Bacillus tuberculosis was not 

 discovered until 1881), and considering the short time devoted to 

 its study it is surprising to see how much has been accomplished. 

 Complicated apparatus has been devised, books have been pub- 

 lished in many languages, new methods in photography have 

 been invented, and results have been recorded with an accuracy 

 and system that are very gratifying. If the germ theory of 

 disease is the true one, then any research which broadens our 

 knowledge of bacteria must be ranked as in the highest degree 

 humanitarian ; and if through these researches we shall come to 

 a better knowledge of disease and how to combat it, not only will 

 the truth of the theory be demonstrated, but the world will con- 

 fess that the microscope has a practical value greater than that of 

 a scientific toy. 



The bacteriologist must be able to determine in regard to a 

 family's or city's water supply, its richness in bacteria, and 

 whether the germs contained are harmful to health. All water, 

 even distilled water, and that which has passed through an ordi- 

 nary charcoal filter, contains germs. Only by the severe tests of 

 the bacteriogical laboratory can we say positivelv whether a given 

 water supply is contaminated by sewage, and whether the filter 

 used for its purification is effective in removing germs. 



The speaker gave a complete description of the methods pur- 



* From a paper read at the San Francisco Microscopical Society. 



