BACTERIOLOGICAL TECHNIC. 



55 



Also make streak inoculation in tube slants by simply passing the infected 

 platinum needle over the middle of the tube slant surface, from lower end 

 toward the top, observing the instructions regarding the cotton plug and 

 needle sterilization, with each tube inoculation. Number the tubes seri- 

 ally, and in a special notebook make entry of all desirable data pertaining 

 to each inoculation, making such entries under each tube number. Place 

 tubes vertically in a suitable holder, as tumbler, beaker, wire basket, etc., 

 and set aside in incubator or in some container to which you alone have 

 access. 



In warm weather the first bacterial growths may appear at the end of 

 thirty-six hours. In cold or cool weather nothing may appear for two, three, 

 and even four to five days. Note the nature of the bacterial growth in a 

 deep stab inoculation and in the streak inoculation, as to 



Fig. 32. — Making an Esmarch roll-tube culture. A lump of ice is placed in a dish 

 and the inoculated tube is placed horizontally in a groove in the ice and revolved undl the 

 medium is well set. The groove may be made with test-tube full of hot water. 

 {Williams.) 



a. Growth — scanty, moderate, abundant, slow, rapid. 



b. Form of growth— outlme clearly defined, spreading, rugose, beaded, etc. 



c. As to surface'— Qa,t, raised, concave, convex. 



d. CoZo;-— translucent, glistening, waxy, transparent, opaque, light, 

 chalky white, grayish-white, dark red, green, blue, yellow, lemon color, 

 purple, etc. 



e. Odor — comparative description. 



f. Consistency— viscid, slimy, stringy, membranous, friable or brittle, 



dry, watery, etc. 



g. Changes in medium— gdaXin liquefied, gelatin not liquefied; colored, 

 as grayed, browned, reddened, blued, etc. In case indicators are used, the 

 possible color changes should be noted. 



