554 Dr. E. W. A. Walker [Feb. 18, 
any sense be regarded as permanent, but would seem to be due to merely 
temporary changes in the metabolism of the organisms concerned. | 
Lest it should be thought that the alterations in reactions which have 
been here described are not of absolutely fundamental, character, I have 
compared a number of my induced varieties as nearly as possible with the 
types and variants described by Andrewes and Horder. For this purpose it 
is necessary to omit their neutral red and coniferin tests, which I have not 
used, and to disregard the questions of growth in gelatin and length of 
chains in bouillon. These latter do not appear to form very important 
features in their system of classification. The facts, however, must 
be fully borne in mind in estimating the value of the present criticism. 
Their streptococcal types are numbered (1) pyogenes, (2) salivarius, 
(3) anginosus, and (4) feecalis; the variants being indicated by the letters 
a, 0, ¢, a, ete. 
Among my streptococci derived from L are to be found (with the 
provision just mentioned) the following types and variants of Andrewes and 
Horder in succession :—3 ¢, 1d, 39,46, 1d, 4¢, 3z,1d, and a form not met 
with by these writers. That is to say, L appears to correspond at different 
times in my experiments with variants of S. pyogenes, S. anginosus, and 
S. fecalis in their classification. P gives la, 3h, 1d, 3e, of Andrewes and 
Horder, again pyogenes, anginosus, and fecalis, as well as other forms not 
found by them, and similarly with others of the streptococci. 
The conclusion, therefore, is apparently unavoidable that, in spite of the 
very extended observations of Gordon, Houston, and Andrewes and Horder 
on the streptococci, there is still no evidence of the existence in the human 
subject of more than one micro-organism, Streptococcus, though this may 
vary as greatly in its chemical reactions in different cases as it is known to 
do in virulence. This view agrees with those consistently advanced by 
Marmorek and others. 
A paper has quite recently appeared by C. O. Jensen giving an account: 
of investigations carried out by him and his co-worker Holth on a number 
of micro-organisms, including streptococci, by the application of a long 
series of chemical and biological tests. Jensen states that Holth has 
examined 150 different strains of streptococci in relation to all the carbo- 
hydrates and polyvalent alcohols which he could obtain, and to a number of 
slucosides in addition. The conclusion arrived at is that culture in bouillon 
containing these substances, followed by titration of the reaction affords 
a valuable means of identification, differentiation, and classification of these 
organisms (the italics are mine). These observers regard lactose, trehalose, 
cellobiose, and gentobiose as of great value for the purpose of classification, 
