Methods of Determination of Pathogenic Microbes. 115 



They are then passed tlirough the Gram iodiue 

 solution, or a, five per cent solution of sodium car- 

 hoiiate, through water, alcohol, etc. This method is 

 well adapted for the staining of charbon material. 



Method of staining spores in bacilli. — To stain spores 

 dried on the cover glass they are immersed for a few 

 minutes in hot Ehrlich's solution and washed in 

 alcohol; the cover glass is then held for a second 

 in methylene blue, washed again in alcohol, and 

 mounted in balsam. The bacilli are blue, the spores 

 are red when they have attained their development, 

 uncolored whilst they are in way of formation. 



II. Culture of germs. 



The majority of pathogenic germs can be culti- 

 vated in appropriate artificial media placed under 

 suitable conditions of temperature. Our aim not be- 

 ing to publish a complete treatise on the technique of 

 bacteriology, we will refer the reader for details upon 

 this point to special works on the subject, and limit 

 ourselves to the general principles of the question. 



We will review, in succession, the methods of ster- 

 ilization, the composition and preparation of the va- 

 rious culture media, the sowing of these media and 

 establishing them at a suitable temperature, the physi- 

 cal and chemical characters which the cultures may 

 present and the preservation of these cultures. 



Sterilization. 



The objects and instruments which are employed 

 in the culture of microbes must be previously freed 

 from all living germs. Sterilization is obtained by 

 different means : heat, filtration, antiseptics. 



