x] BACILLI . SPECIAL 19^ 



discoverable, in others their number mounts up to eight 

 or even in single cases to ten flagella. The production of 

 gas bubbles in shake cultures notifies great differences. 

 While the typical bacillus coli forms gas bubbles copiously and 

 rapidly in 24 — 48 hours, there are varieties which produce 

 gas bubbles under these conditions later, or very late — 

 8 — 10 days or not at all. The same holds good as to 

 milk curdling : varieties exist which either curdle milk at 

 37° C. after several days, or after many days — as late as 

 20 — 25 days. And, finally, the indol reaction of broth 

 cultures is in some varieties to be obtained after many 

 days' growth, and in others, otherwise behaving like typical 

 bacillus coli, is not at all obtainable. 



Mr. Mervyn Gordon, who has devoted in my laboratory 

 special attention to these varieties, has isolated from the in- 

 testinal contents in health and disease, from waters, and from 

 sewage, a number of varieties which in respect of length, 

 motility, and number of flagella, of the power of gas- 

 formation, of the power of curdling milk, and of the power 

 of indol-formation in broth cultures, furnish quite a 

 respectable number. Thus he found varieties which in all 

 respects compare with the typical bacillus coli except that 

 it has eight flagella, or that it is pronounced cylindrical, 

 or that it does not form gas, or that it does not curdle 

 milk till very late, or that it does not form indol in broth 

 culture ; then he found varieties which, except in two 

 of these characters combined, have all other characters ; 

 and so on to a variety which by the mode of growth in 

 plate and streak and on potato, and by the flagella, is bacillus 

 coli, but has no other character of bacillus coli, in that it does 

 not form gas, does not curdle milk, and does not form indol. 



The typical bacillus coli is a strong producer of acid. 

 This can be shown very strikingly by using for culture 



