136 



BACTERIA 



for over one hundred days in pus. Dry thermal death-point is 80 

 C. for one hour. Moist heat 70 C., kills in ten to twenty minutes. 

 Resists freezing temperature for many months. 



Exceedingly resistant to formaldehyde, more so than some 

 spore-bearing organisms. Resists light also. 

 It is killed by corrosive sublimate i-iooo 

 in 15 minutes; i percent H 2 O 2 in 30 minutes. 

 Chemical Activities. Produces a golden 

 yellow pigment only under oxygen. Gen- 

 erates acids, but no free gases. Creates 

 indol and sulphuretted hydrogen; ferments 

 urea, and produces ferments that dissolve 

 gelatine, and the coagulated proteids of 

 milk. The toxin is soluble in water, and 

 acts intensely, causing violent local reaction. 

 If in the abdominal cavity, it causes perito- 

 nitis. Subcutaneously it may produce sterile 

 abscess, or local necrosis. There is pro- 

 duced in cultures a toxin having a destruc- 

 tive action upon leucocytes and red blood 

 cells. 



Cultures.- In gelatine it rapidly forms 

 golden yellow colonies, that quickly liquefy 

 the gelatine. (Fig. 42.) Sterile products 

 of the growth also liquefy gelatine. On 

 gelatine plate, yellowish to orange colonies 

 FIG. 42. Gelatine cul- are formed. On agar streak a luxuriant 



. 



is a marked even cloudiness, with a fine 

 pellicle on surface; moderate sediment, which upon shaking is 

 broken up. Milk is rendered acid and curdles very soon, the curd 

 being digested finally. 



Potato cultures are dry, whitish, then yellow, and finally deep 

 orange. 



