THE BACTERIA OF THE MOUTH 99 



organism. Note the name of the genus to which each colony 

 belongs. , 



Give a summary of the genera of bacteria present on the 

 plates with the approximate number of colonies of each. 



Make i or more cover-glass preparations from the mouth 

 and stain with alkaline methylene-blue. Note carefully the 

 varieties of bacteria it contains. 



Inoculate from the unnamed cultures furnished such media 

 as the requirements of the next exercise demand. 



150. Making Cover-glass Preparations from the Mouth 



These can be made from the sputum, expectorated in a watch- 

 glass, or from the scrapings from the tongue, gums, pharynx, or 

 from the base of the teeth. If any of the latter sources are 

 chosen, the part from which the material is to be taken should 

 be scraped carefully with a sterile (flamed) platinum loop or 

 with the blunt point of a scalpel or other stiff instrument. The 

 scrapings are spread on cover-glasses the same as the sputum. 



