BACTERIOLOGICAL ANALYSIS. 661 



The Classification of Diphtheroides. — The biochemical method 

 here should include immunity tests with a standard antitoxin. 

 This is the surest test of the specific nature of a suspected diph- 

 theroid organism. Opinion is divided as to the extent value of 

 the sugar reactions for the differentiation, but from the writings of 

 Arkwright, Graham Smith, Hiss and Zissner, and from observa- 

 tions in this laboratory, I am convinced of the great value of these 

 tests. Glucose, mannit, lactose and cane sugar solutions in 

 peptone water are used, as we find these quite satisfactory and 

 infinitely more easy to prepare than the serum water media of Hiss. 

 The typical reaction for true diphtheria is to produce acid on 

 glucose and nil on mannit, lactose, or cane sugar. In two of our 

 cases there was no appearance of acidity on glucose with cultures 

 believed to be diphtheria. Hoffman's bacillus gives no acidity on 

 any of the sugars. Various other diphtheroids ferment mannit or 

 saccharose, and thus can be excluded with certainty. In several 

 cases Dr. Cleland informs me he has found the sugar reactions of 

 great value in differentiating diphtheroids from the true diphtheria 

 bacillus. The following case illustrates the value well. Five 

 cultures were taken from children believed to be suffering from 

 wound diphtheria, and one from a child in the same hospital with 

 true throat diphtheria. Diphtheroid bacilli were found in all cases. 

 These cultures were tested on the sugars ; one only gave the 

 reactions of B. diphtheria. The others all agreed, having diph- 

 theroid reactions, fermenting saccharose as well as glucose. The 

 culture giving the reactions of true diphtheria was pathogenic to 

 guineapigs and was protected against by antitoxin. One of the 

 " diphtheroid " cultures was tested and was non-pathogenic to 

 guineapigs. 



The Biochemical Method Applied to the Classification of Other 

 Organisms. — I had intended to refer somewhat fully to the possi- 

 bility of the application of the biochemical method to the classifi- 

 cation of other organisms, but on considering the matter I deter- 

 mined to conclude this paper at this point. 



If I have fulfilled my intended object, which was to show how 

 valuable are the " sugar" tests as apphed to two great groups of 

 organisms, and especially how absolutely necessary they are in 

 the identification of members of the colon family, I am well 

 satisfied. The amount of systematic work done in the application 

 of the above methods to other groups of organisms, notably the 

 streptococci, certain of the diplococci, is considerable, but hardly 

 of such a nature as to condense into a paper of this nature. Later 

 I hope to group together this work, together with work done by 

 myself and my colleague, Dr. Cleland ; at present I will simply 

 conclude by saying that I believe that it will be demonstrated 

 that the sugar reactions will prove almost, if not equally useful on 

 several other groups of bacteria, and that in the method lies one 

 of the greatest aids to systematic bacteriology. 



