376 Dr. W. Huut.-r. '/'/ Influence of 



debted to Professor Japp, F.R.S.) The formula is there given as 

 CeH3(OH)(SO 3 H)COOH ; and its formation by the action of sulphuric 

 anhydride on salicylic acid (Mendios, 'Ann. Chem. Pharm," vol. 103, 

 p. 4), or by heating salicylic acid with concentrated sulphuric acid 

 (Remsen, ibid., vol. 179, p. 107). It is said to be very stable, and to 

 undergo no change on heating with nitric acid. 



The specimens of salicyl-sulphonic acid which I have used in my 

 experiments were obtained from Messrs. Davidson and Kay, Union 

 Street, Aberdeen. 



III. " The Influence of Oxygen on the Formation of PtomaincR." 

 By WILLIAM HUNTER, M.D., F.R.S.E. Communicated by 

 Professor M. FOSTER, Sec. U.S. Received March 11, 189 ' 



(Abstract.) 



A special interest attaches to the role of oxygen in the life-hisl 

 of bacteria. Very wide differences exist, however, between diff< 

 groups in respect of its importance. To the great majority a 

 supply of oxygen is absolutely essential for their proper growth ai 

 development ; to a small minority the converse applies, growth 

 proceeding best in the absence of oxygen, if indeed it is not entirely 

 prevented by its presence ; while, lastly, in the case of an inter- 

 mediate group it seems almost immaterial whether oxygen be present 

 or not, growth proceeding apparently equally well in both conditions, 

 provided that the supply of food be otherwise suitable. 



Of these three groups of " obligate aerobic," " obligate anaerobic " 

 and " facultative aerobic " bacteria, respectively, the last has perhaps 

 the greatest interest for the pathologist, as it is to it that the great 

 majority of pathogenic organisms belong. 



The question is thus an interesting one, to what extent the patho- 

 genic properties of this class of bacteria are related to the power they, 

 apparently under necessity, possess of obtaining their supply of 

 oxygen from the food constituents themselves when the supply in 

 the air is cut off. 



The present paper deals with the results of an investigation un< 

 taken in this relation. 



It was necessary that the class of bacteria selected for study should 

 be one whose pathogenic properties were not constant, but subject to 

 variations presumably connected with the character of their sur- 

 roundings. 



The bacteria of ordinary putrefaction possess in a special degree 

 this qualification, their chemical products differing much in char 

 and poisonous action under different, for the most part as yet un- 

 known, conditions. 



