BACILLARY DYSENTERY. 349 



the patches are much diminished and therefore there are fewer 

 cast off into the intestinal lumen, and that in addition there is a 

 correspondingly great increase of the B. coli, which thus causes 

 any typhoid bacilli in a plate to be quite outgrown. From the 

 fact that the ulcers in a case of typhoid may be very few in 

 number, it is evident that there may be at no time very many 

 typhoid bacilli in the intestine. We may add that the micro- 

 scopic examination of the stools is useless as a means of 

 diagnosing the presence of the typhoid bacillus, 



Isolation from Water Supplies. A great deal of work has 

 been done on this subject. It is evident that if it is difficult to 

 isolate the bacilli from the stools it must a fortiori be much more 

 difficult to do so when the latter are enormously diluted by 

 water. The B. typhosus has, however, been isolated from water 

 during epidemics. This was done by Klein in the outbreaks in 

 recent years at Worthing and Rotherham. The B. coli is, as 

 might be expected, the organism most commonly isolated in 

 such circumstances. In the case of both bacteria, the whole 

 series of culture reactions must be gone through before any 

 particular organism isolated is identified as the one or the other ; 

 probably there are saprophytes existing in nature which only 

 differ from them in one or two reactions. In the examination 

 of water, the addition of .2 per cent carbolic acid to the medium 

 inhibits to a certain extent the growth of other bacteria, while 

 the B. typhosus and the B. coli are unaffected. In examining 

 waters, the ordinary plate methods are generally used. Klein, 

 however, niters a large quantity through a Berkefeld filter, and, 

 brushing off the bacteria retained on the porcelain, makes 

 cultures. A much greater concentration of the bacteria is thus 

 obtained. On the whole there is little to be gained from this 

 attempt to isolate the typhoid bacillus from water in any 

 particular case, and it is much more useful for the bacteriologist 

 to bend his energies towards the obtaining of the indirect evi- 

 dence of contamination of water by sewage, to the nature of 

 which attention has been called in Chapter IV. 



BACILLARY DYSENTERY. 



Dysentery has for long been recognised as including a number 

 of different pathological conditions, and within more recent times 



