HppenMy* 



METHODS OF INVESTIGATION FOR BACTERIA. 



457. Since the methods employed in Bacteriology differ 

 in many respects from those used in the study of other 

 plants, I have preferred to collect the former into a special 

 chapter. In the following pages I have not attempted to 

 give an even approximately exhaustive compilation of bac- 

 teriological methods. I have rather chosen to bring together 

 a number of trustworthy methods of preparation which 

 should be quite sufficient for most cases in the study of 

 Bacteria. I must refer persons who wish to devote them- 

 selves especially to Bacteria to the special works on the 

 subject, particularly those of Gunther (I) and Hueppe (I). 



I. The Observation of Living Bacteria. 



458. The observation of living Bacteria may be generally 

 conducted like that of other lower organisms. If it is to be 

 continued for a long time, the Bacteria may best be placed 

 in a hanging drop (cf. 2). Under some circumstances, a 

 frequent renewal of the culture-fluid is necessary. 



In case of rapidly motile Bacteria, they may be brought 

 to rest by proper fixing media, like the fumes of iodine or 

 of osmic acid. 



Finally, I may remark that, in some cases, the dark-field 

 illumination of the Abbe condenser may be used with suc- 

 cess in the examination of Bacteria. 



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