9° 



PHARMACEUTICAL BACTERIOLOGY. 



(concave center) are required. Touch a small drop of the culture to be 

 examined on the center of a clean and heat-sterilized cover-glass, by means 

 of a heat-sterilized platinum wire loop. Smear a little plain petrolatum 

 around the rim of the concavity of the slide and invert the cover-glass prep- 

 aration upon the slide, pressing it gently in place on the petrolatum. 



Fig. 43.— Jeffer's circular counting plate for Petri dish cultures. The entire area (100 sq. 

 cm.) is marked off into ten equal sectors of ten sq. cm. each. 



[ Examine for a period of several hours or longer as may be desired. Cell 

 division, spore formation, etc., can be studied very conveniently. Observa- 

 tions on the effects of temperature and rate of septation may be made. The 

 hanging-block preparation is made by touching the surface of a cube of 

 nutrient agar with the bacteria and then applying this bacterial side against 



