ABOUT CHOLERA 243 



exist, and the inquiry is at the present moment proceeding 

 in Paris. 



A very striking and at first sight astonishing fact in 

 regard to this subject is that there are a very large 

 number and variety of microbes habitually present in the 

 human digestive tract. There are so many different kinds 

 differing altogether from one another in their chemical 

 action which are present in greater or less abundance in 

 this tract from one end to the other, that no one is at 

 present able to say even approximately how many there 

 are, nor to give anything like a complete account of their 

 properties. The fact is that their isolation and study, 

 and the definite determination of their properties, is not 

 an easy job. Many workers are engaged on it, and it 

 will be years before the matter is threshed out. One 

 most curious result of these studies is that a person may 

 have the cholera-bacillus in his intestine not growing 

 with any activity, but still alive and yet be perfectly 

 well. He can, therefore, carry the cholera-bacillus from 

 one locality to another and spread the disease, and yet 

 be entirely devoid of suspicion, free himself from disease, 

 and certified as healthy ! The same is true of the bacillus 

 of typhoid fever. Persons who have had typhoid fever 

 have been shown to retain the typhoid-bacillus flourishing 

 for as long as fourteen years afterwards in their intestine, 

 without any ill effects to themselves, and to have been the 

 constant source of infection and disease to those living in 

 the same house with them by spreading the bacillus. 

 The classical case of this is that of a woman who carried 

 on a baker's business at Strasburg. Infection by and 

 protection from microbes is by no means so simple a 

 thing as it is sometimes represented to be. 



Now that we are quite sure as to Koch's comma-bacillus, 

 or spirillum, being the definite poison-producing agent 

 causing Indian cholera, it is comparatively easy to under- 



