6o 



PHARMACEUTICAL BACTERIOLOGY. 



3,000,000; and the percentage of moisture was 10. From these data it would 

 be found that i gm. of dry soil will contain 3,855,011 microbes. 



The above is sufl&cient to make clear how one might proceed to deter- 

 mine the number of microbes in and upon old pills, tablets, powders; on one 

 ivory vaccine tip, in one glycerinated vaccine tube, in i c.c. of bacterial 

 vaccine, antitoxin, syrup, tincture, fluidextract, camphor water, distilled 

 water, sewage, drinking water, etc. Naturally, great caution and care must 

 be observed to avoid errors and faulty conclusions. In fact, no one should 

 attempt such work in actual practice until after considerable preliminary 

 laboratory experience. 



It is not practicable nor is it necessary to give fuller information regarding 

 bacterial cultures. We have not touched upon the various methods for 

 determining whether or not the microbes under investigation are essentially 



Fig. 37. — Graduated fermentation tube. These tubes are required for gas determination 

 with colon bacillus and other gas-forming micro-organisms. 



aerobic or essentially anaerobic; the manner of determining the thermal death- 

 point; relationship of rate of growth to temperature, etc. We have said 

 nothing of the use of indicators added to culture media, as litmus, rosolic 

 acid, and phenolphthalein, nor have we explained the special use of special 

 culture media in determining the nature and identity of bacteria. These 

 and many other details we must omit, merely stating that, should it become 

 desirable to make such investigations, the necessary information must be 

 secured elsewhere, as in some standard laboratory guide in bacteriological 

 technic. 



The following outline of special methods will serve as a guide in making 

 bacteriological examinations of soils, air, pharmaceuticals, liquids, etc. 



D. Culturing Soil Bacteria. — Soil is a mixture of dead and decayed organic 

 matter, sand and living organisms and their spores. Near the surface the 

 soU contains large numbers of bacteria, from 10,000 to 10,000,000 per gram 



