Methods of Determination of Pathogenic Microbes. 121 



a very short neck, which is surmounted by a ground 

 glass hood ; the latter is prolonged by a narrow tube 

 which is closed by a plug of wadding. These ves- 

 sels may be replaced by conical vials, etc., but the 

 latter have the great inconvenience of allowing a too 

 rapid evaporation of the liquid. 



In filling the Pasteur vessels, which must previously 

 have been sterilized, we employ with advantage a 

 Chamberland pipette. This is a flat bottomed bulb 

 with a long narrow tube bent to 45° and filled at 

 one part of its length by a plug of wadding; from 

 the side of this bulb projects horizontally a long slen- 

 der tube sealed with the flame at its free extremity. 

 The pipette having been sterilized, the lateral tube 

 is flamed, the point broken off in the sterile bouillon 

 and the latter slowly aspirated into the pipette. This 

 done, a quantity (half to one centimeter in depth) of 

 the bouillon is allowed to flow into the Pasteur 

 culture vessels, the latter being held in the horizontal 

 position, in order to avoid the entrance of air germs; 

 this operation should be conducted in a room free from 

 currents of air. The bouillon having been introduced 

 into the culture vessels, it is advisable to test if these 

 are really sterile by placing them during two or three 

 days in an incubator ; those in which the bouillon be- 

 comes turbid contain bacteria and consequently must 

 be rejected.* 



* [Usually the culture media, both fluid and solid, are filled into 

 ordinary test-tubes, closed with cotton and sterilized in the steam 

 sterilizer. Evaporation is to a large extent prevented by accu- 

 rately fitting a piece of tin-foil over the mouth of the tube. — D.] 



