CHOLERA. 427 



In puncture-cultures in gelatin the growth is again so 

 characteristic that it is quite diagnostic (Fig. 91). The 



■ JNMBU 



Y\G. 91. — Spirillum cholera Asiatica ; gelatin puncture-cultures aged forty- 

 eight and sixty hours (Shakespeare). 



growth takes place along the entire puncture, but devel- 

 ops best at the surface, where it is in contact with the 

 atmosphere. An almost immediate liquefaction of the 

 medium begins, and, keeping pace with the rapidity of 

 the growth, is more marked at the surface than lower 

 down. The result of this is the occurrence of a short, 

 rather wide funnel at the top of the puncture. As the 

 growth continues evaporation of the medium takes place 

 slowly, so that the liquefied gelatin is lower than the 

 solid surrounding portions, and appears to be surmounted 

 by an air-bubble. 



The luxuriant development of the spirilla in gelatin 

 produces considerable solid material to sediment and fill 

 up the lower third or lower half of the liquefied area. 

 This solid material consists of masses of spirilla which 

 have probably completed their life-cycle and become 

 inactive. Under the microscope they exhibit the most 



