ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 455 



The foregoing results were obtained under anaerobic conditions ; 

 when the conditions are altered different decompositions take place. 



Life-History of Bacillus coli communis.* — Dr. W. C. C. Pakes 

 concludes, from a large number of observations of varieties of B. coli, 

 that they fall under distinct types. Of those studied, fifty-two were 

 typical, morphologically and pbysiologically ; all of these were motile. 

 In doubtful cases, motility was best tested in cultures in dextro-glucose 

 broth. The typical B. coli does not stain by Gram's method, and does 

 not sporulate ; it produces indol and gas. It coagulates milk, but not 

 at 20°, and in extreme cases curdling may be delayed for twelve days. 

 Dextro-glucose is fermented when B. coli is grown in sodium formate 

 broth, the formate being decomposed into carbon dioxide and hydrogen. 

 The gas evolved causes frothing of the medium, while no such result 

 occurs with B. typhosus. Not only the typical members, but all of the 

 coli group, including the typhoid bacillus, reduce nitrates to nitrites. 

 None decompose urea. All the varieties produce hydric sulphide, and 

 this was shown by inoculating pepton water to which a lead salt had 

 been added. The colon bacillus reduces a 5 p.c. solution of neutral 

 red, converting it into a fluorescent yellow ; the typhoid bacillus has 

 no such action. Proteus vulgaris and B. prodigiosus have the same 

 reducing action as B. coli. Some of the typical colon bacilli ferment 

 glucose, some glycerin, some both, and some neither. 



Modification of the Functions of Bacillus coli.f — L. Grimbert and 

 G. Legros, by cultivating five different types of B. coli under various 

 abnormal conditions, deprived two of the varieties of their power to 

 produce indol, but the power to ferment lactose was unaffected. 



Varieties of Bacillus coli isolated from Typhoid and Normal 

 Dejecta.} — Dr. W. H. Horrocks examined normal and typhoid dejecta 

 in the hope of discovering cultural characteristics or reactions to specific 

 sera, by which varieties of B. coli occurring on typhoid stools might be 

 distinguished from those in normal dejecta ; so that, even if B. typhosus 

 were not detected, some criteria would be obtained for indicating that 

 a water had been fouled by typhoid organisms. 



The conclusions arrived at were that, as far as cultural characters 

 are concerned, there appear to be no types of B. coli in typhoid stools 

 which display sufficiently constant characters to enable them to be 

 distinguished from the varieties of B. coli found in normal stools. 



As regards reaction to antityphoid horse serum, the varieties of 

 B. coli isolated from typhoid stools show much greater sensibility to 

 agglutination than the varieties of B. coli isolated from healthy stools. 

 Consequently, if varieties of B. coli isolated from a water supply are 

 found to be agglutinated with antityphoid horse serum diluted 1-500, 

 it would seem that there are reasonable grounds for the assumption 

 that the water supply in question has been fouled with the specific 

 dejecta from cases of enteric fever. 



Pathogenic Bacilli intermediate between the Typhoid and Colon 

 Groups. § — Dr. H. Cushing made a comparative study of some members 



* Brit. Med. Journ., 1901, i. p. 958. 



t Journ. Pharm., xiii. (1901) pp. 107-9. See Journ. Chera. Soc, lxxx. (1901) 

 Abstr., ii. p. 265. 1 Journ. Hygiene, i. (1901) pp. 202-13. 



§ Bull. Johns Hopkins Hosp., xi. (1900) pp. 156-70 (10 figs.). 



