Report on the Bacteriology of Water. 403 



Potatoes. Produces an almost invisible greyish-white growth after 

 forty-eight hours, but on touching the moist-looking surface with the 

 needle a tough resistant pellicle is found. On some potatoes, how- 

 ever, its growth is more apparent, so that the above is not the only 

 appearance to which it may give rise. 



Blood Serum. Produces a milk-white expansion restricted to the 

 path of the needle. 



Broth. Benders it turbid. 



Milk. Grows abundantly, rendering it slightly acid. No coagula- 

 tion takes place. 



Remarks. Tt grows best at about 37 C. Kitasato states that it 

 produces no indol reaction. It produces sulphuretted hydrogen in 

 iron-gelatine, the needle-track after from five to six days becoming 

 intensely black in colour. In iron-agar, at from 33 to 34 C., this 

 black colour appears at the end of 24 hours (Fromrne). It produces 

 sulphuretted hydrogen in broth with or without peptone ; compara- 

 tive tests made with the B. coli communis revealed no difference either 

 in the degree of the reaction (as shown by the lead-paper test) or in 

 the rapidity with which it took place in the case of the two organisms. 

 The typhoid bacillus never produces gas in any artificial media. It 

 is destroyed when heated for ten minutes at 60 C. 



Injection into the aural vein of rabbits causes death in 24 28 

 hours (Fraenkel and Simmonds), guinea-pigs into which the cultures 

 are introduced by the mouth, as described for cholera, are also killed 

 (Seitz). Opinion is, however, still divided as to whether death is 

 due to mere intoxication by the bacterial products present in the 

 cultures, or to actual multiplication of the bacillus within the animal. 

 In this connection, see Petruschky (' Zeitsch. f. Hygiene,' vol. 12, 

 1892, p. 269). 



Bacillus Coli Communis. 



Authority. Escherich, ' Fortschritte der Medicin,' vol. 3, 1885, 

 Nos. 16 and 17. Also Dunbar, " Ueber den Typhus-bacillus und den 

 Bacillus Coli-communis," ' Zeitschrift f. Hygiene,' vol. 12, 1892, p. 

 485. Also Luksch, " Zur Differen/ialdiagnose des Bacillus typhi ab- 

 dominalis (Eberth) und des Bacterium Coli-commune (Escherich)," 

 * Centralblatt f. Bakteriologie,' vol. 12, 1892, p. 427. 



Where FoimdIn the intestinal tract of man and animals. Found 

 often in water by numerous investigators, and frequently mistaken 

 for the typhoid bacillus. 



Microscopic Appearance. The typical form is a short bacillus 0'4 ;t 

 broad and 2 to 3 ft long ; it is, however, very variable, oval indi- 

 viduals and forms resembling cocci being also found. It exists 

 chiefly as a double bacillus arranged in groups. It is slightly motile, 

 and is provided with 1 to 3 cilia, whilst the typhoid bacillus has 8 to 



