and Laboratory Methods. 



1609 



PREPARATION OF BACTERIA. 

 Preparations of bacteria for examination under the microscope are, in the 



main, easy to make. The apparatus needed is simple and easy to manipulate. 



A pair of Cornet forceps, a pair of plain cover-glass forceps, an inoculator, con- 

 sisting of a glass rod about 



eight inches long with two 



and one-half inches of 



No. 27 gauge platinum 



wire sealed into one end 



of the rod, some clean 



covers, slips, staining solutions, Canada balsam, and a Bunsen burner or alcohol 



lamp are about all that will be required. 



To make a mounted preparation, the platinum wire in the inoculating rod 



should be bent into a small loop 

 at the end. It should then be 

 heated over the alcohol or Bun- 

 sen flame until it is red hot, to 

 sterilize it. A little of the ma- 



Comet's Forceps. 



Cover-glass Forceps. 



terial to be examined should be taken up by this loop and spread thinly on a 

 cover-glass held in a Cornet forceps. Before laying down the inoculator it should 

 be reheated to sterilize it and prevent the carrying of infection. Allow the thin 

 film of material on the 



cover-glass to dry in the t^^^^" ir' -^^^ v- :.- ^ ^r^v ,,, r^ ' ' i — 



air, then pass it through Inoculating Needle. 



the flame of the alcohol 



lamp or Bunsen burner three times rapidly, being careful to keep the film surface 

 upward. It is now ready for staining, and may be stained with almost any of 

 the anilin dyes. The stains most generally used are Loeffler's alkalin methylen 

 blue, gentian violet, and methyl violet. These stains may be purchased ready 

 for use or may be prepared according to the following formulae : 



loeffler's alkalin methylen blue. 



Concentrated alcoholic solution of methylen blue 



Caustic potash, one per cent, solution 



Distilled water ...... 



GENTIAN VIOLET. 



Gentian violet, saturated alcoholic solution 

 Absolute alcohol ...-.- 



Anilin oil, clear three per cent, in distilled water 



METHYL VIOLET. 



30 c. 



1 c. 



100 c. 



Methyl violet 



Dissolved in absolute alcohol 



Anilin water . . - 



11 c. c. 



10 c. c. 



100 c. c. 



1 gram. 

 20 c. c. 



80 c. c. 



Make the anilin water for either formula as follows : Shake up three c. c. 

 of clear anilin oil in 100 c. c. of distilled water. Shake thoroughly several times 

 and filter till it is clear, when it is ready for use. These stains are applied to the 



