524 APPLICATION OF METHODS OF BACTERIOLOGY 



In employing this culture medium it is necessary to have 

 a uniform suspension of a portion of the material to be 

 examined and to make a series of plate inoculations from 

 this suspension by smearing carefully the material under 

 consideration over the surface of the medium in the plates, a 

 sterile platinum spatula or a sterile bent glass rod being used 

 for the purpose. 



After fourteen to sixteen hours at 37 C., and still better 

 after twenty to twenty-four hours, the cultures are readily 

 differentiated : 



a. Bacillus Coli: All cultures of true colon that have been 

 examined form colonies of 2 to 6 or more millimeters in 

 diameter, of reddish color and translucent. In each intes- 

 tinal evacuation there are usually several varieties of 

 colon colonies which differ according to their size and tex- 

 ture, translucency, and- the intensity of the alteration of 

 the color which they bring about. Many colon colonies 

 are bright red, some are cloudy, and others are quite opaque, 

 dark-wine red in color, while still others form large colonies 

 which are surrounded by a red halo. 



b. Bacillus Typhosus: The colonies have a diameter of 

 1 to 3 millimeters, rarely larger. Their color is blue, with 

 a tendency toward violet. In structure they are glistening, 

 with a single contour, somewhat of the nature of a dew drop. 

 Only in isolated instances is the colony larger and more 

 cloudy in appearance. 



The Endo Media. (Modification of Kendall and Day.) 

 Prepare the following : 



(a) Water 1000 c.c. 



Powdered agar-agar 15 grams 



Peptone (Witte) 10 grams 



Meat Extract (Liebig) 3 grams 



