50 BACTERIOLOGICAL EXAMINATION OF WATER. 



its quicker growth on gelatine plates, its power of developing at 

 5 C., and the absence of all traces of agglutination with anti- 

 typhoid serum. 



Two other organisms have been described which have received 

 the name sulcatus ; they are easily differentiated from the bacilli 

 isolated by Weichselbaum. 



B. Sulcatus Liquefaciens. 



This organism is described by Fliigge, and said to be frequently 

 found in water. It is a medium-sized motile bacillus which does 

 not form spores. The colonies in the depth are small, round, 

 slightly granular and yellowish in colour. The surface colonies 

 are larger, thin and transparent, and have an irregular margin ; 

 the surface of each colony also shows a fine system of ridges and 

 furrows like the typhoid bacillus. Liquefaction slowly sets in 

 and the colonies sink in the gelatine. On agar there is a thin 

 grey transparent growth. On potato a yellowish- brown layer 

 appears. 



B. Aquatilis Sulcatus. 



This bacillus is often found in water supplies and in many 

 respects resembles the organisms in Group III. It is a rather 

 large bacillus, which forms spores, and has a slow waddling move- 

 ment like B. subtilis. It does not stain with Gram. The 

 colonies in gelatine plates closely resemble those of B. subtilis, 

 but the liquefaction is not so rapid. On agar it produces a dry 

 wrinkled growth. In broth there is a diffused growth, and later 

 a wrinkled film forms on the surface. Milk is coagulated and 

 slowly digested. On potato there is a white, dry, slightly folded 

 layer. In glucose media there is no gas formation. Indol is not 

 produced in peptone and salt solution, and the reaction of 

 litmus- whey remains unchanged. 



GROUP III. 



This group includes the three varieties of the "potato 

 bacillus," viz. : the B. mesentericus vulgatus, B. mesentericus 

 fuscus, and the B. mesentericus ruber. Fliigge includes in the 

 group of the " hay bacilli " the above organisms and also the 

 following : B. subtilis, B. liodermus, B. mycoides, B. ramosus, 



