SPIRILLUM CHOLERA ASIATICS. 433 



Koch has also made numerous observations with Conditions 

 regard to the action of various inhibiting and destructive 

 agents on the comma bacilli. As regards those hurtful 

 factors, which most frequently cause the death of patho- 

 genic bacteria in nature, namely, drying and overgrowth 

 by saprophytes, it has already been mentioned, when 

 discussing the question of spore formation, that the 

 comma bacilli in all their stages of development die 

 with extraordinary rapidity when dried. If a culti- Drying 

 vation is spread out on a cover glass and exposed to the 

 action of the air at the ordinary temperature the bacilli 

 are found to be dead after 2 to 3 hours, so that no 

 development occurs when such a glass is placed in 

 nutrient jelly. If care is taken to have the culture fluid 

 in a thicker layer it may be somewhat longer, but never 

 more than 24 hours before all the comma bacilli are 

 found to be dead. It follows from the fact of this great 

 sensitiveness with regard to drying, which is present in 

 all the stages of development of the comma bacilli, even 

 in cultures which have been made under the most vary- 

 ing conditions, that no true resting spores are formed. 

 Further, as the result of these experiments, we must 

 draw the important conclusion that no living comma 

 bacilli can be contained in any material which is in a 

 dried or dust-like state ; and as it is only from completely 

 dry surfaces that particles of dust can be detached and 

 carried to other localities by currents of air, it follows 

 that a transport of living comma bacilli by the air, and 

 the production of infection in this way, is impossible. 

 Comma bacilli which are capable of development can Conclusions as 

 only be transported through the air for short distances by currents of 

 when infective fluids are agitated and bubbles are air> 

 detached, as for instance when waves strike against a 

 quay or on the wheels of a water-mill, or in washing 

 cholera linen ; in these cases small bubbles of the fluid 

 containing bacteria may be brought by currents of air 

 into contact with predisposed individuals. 



The comma bacilli are also very easily injured by the Destruction of 

 second factor, namely, the overgrowth by saprophytes, bacilli 

 When mixed with other bacteria they can, if they are 



28 



