I6O BACTERIOLOGY. 



growth takes place very slowly, and only between 

 the temperatures of 30 and 41 C. In about eight 

 or ten days the growth appears as little whitish or 

 yellowish scales and grains (Plate XL, Fig. i). 



The bacillus can also be cultivated in a glass 

 capsule on blood serum, and the appearances of 

 the growth studied under the microscope. The 

 scales or pellicles are then seen to be made up of 

 colonies of a perfectly characteristic appearance, 

 which may be still further studied by making a 

 cover-glass impression (p. 49, and Plate XL, Fig. 

 4). They are then seen to be composed of bacilli, 

 arranged more or less with their long axis corre- 

 sponding with that of the colony itself, and with an 

 appreciable interval between the individual bacilli. 

 The colonies themselves appear as fine curved lines, 

 the smallest being mostly S-shaped. Longer 

 colonies have serpentine twistings and bendings, 

 which often recall the curves of fancy lettering. The 

 ends of the lines run to sharp points, but the middle 

 of the growth is spindle-formed. The youngest 

 colonies are extremely delicate and narrow, but the 

 older colonies increase in size, are thicker across, 

 and, blending with each other, gradually obliterate 

 the characteristic appearances ; a lamellated growth 

 results, which increases, and gives the appearance 

 to the naked eye of the scale or pellicle already 

 described. The blood serum is not liquefied unless 

 putrefactive bacteria contaminate the culture. A 

 fresh tube can be inoculated with one of these little 



