CHOLERA. 169 



bacteria which are formed under various conditions, the same typical naked- 

 eye appearances of the cholera bacillus are always obtained in each case, 

 but on microscopical examination it is found that the first still develops in 

 the form of spiral filaments, the second as comma bacilli, and the third as 

 short bacteria, and that these characteristics are carried on to the fourth 

 generation. 



With all these modifications in form they still produce typical cholera 

 symptoms when injected into the alimentary canal of animals. In addition 

 to these changes there frequently appear at one extremity of the bacillus 

 small cystic dilatations which are due, according to Virchow, to a kind of 

 cedematous degeneration. As these dilatations make their appearance in 

 certain bacilli, others of them shrivel up, and tadpole and spindle-shaped 

 organisms are formed which may break down into small granules and frag- 

 ments. In the later stages of degeneration these various involution forms 

 are completely sterile. In the earlier stages, so long as they take on the 

 aniline colouring matter pretty freely, successful inoculations may usually 

 be made, but if the unfavourable conditions are continued in the new 

 cultivations, the organisms soon lose both their power of taking up the 

 staining reagents and of reproduction. 



It has been stated that the comma bacillus is entirely an 

 aerobic organism, and there can be little doubt that its vege- 

 tative activity is much more marked when the organism is 

 grown in contact with the oxygen of the air. It is certainly 

 more resistant to the action of germicidal agents, and exhibits 

 movements in a much more marked degree. It had been 

 observed, however, that comma bacilli do not cease to multi- 

 ply even when their supply of free oxygen is entirely cut off, 

 but under these conditions, as Wood has pointed out, the 

 bacteria are much more sensitive to external influences, and 

 are very readily destroyed by acids and other germicidal 

 agents. He has found, however, that where free oxygen is 

 cut off, as Pasteur had observed in the case of other ferments, 

 the bacilli produce a relatively much larger quantity of the 

 specific toxine, or poison, than when oxygen is present, 

 and by a number of ingenious experiments he showed that 

 when they were grown on albuminous substances with com- 

 plete exclusion of oxygen, and of substances from which 

 oxygen could be easily derived, the cholera poison was pro- 

 duced more energetically and more rapidly than under the 

 ordinary conditions of aerobic cultivation ; probably because, 

 under these conditions, much larger quantities of albumen 

 must be split up to meet the energy requirements of the 

 organism. 



Wood and Hueppe from this argue that the bacillus gives 

 rise to such important changes in the intestine because there 



