224 
neutral red for reduction, milk for coagulation, 
and the following carbohydrates for acid forma- 
tion: saccharose, lactose, salicin, inulin, mannit 
and raffinose. 
Neutral red has since been discarded by Houston 
as not sufficiently diagnostic. Milk is apparently 
open to the same objection. 
Only the six carbohydrates therefore remain for 
consideration. Houston used them all (and con- 
iferin) in his milk tests, but secured qualitative 
results only. Quantitative ones have been re- 
corded for 300 fecal (human, bovine and equine) 
strains by Winslow and Palmer for dextrose, lac- 
tose, raffinose and mannit. 
Sugar-free broth was used, and the streptococci 
therefore began their growth with an initial acid- 
ity of 1.3 to 2.2 per cent. (deducted from all 
recorded results). After 72 hours’ growth, titra- 
tion (with phenolphthalein) showed the following 
results: 
1. Non-fermenting and fermenting groups are 
found for each of the six carbohydrates tested. 
The dividing line lies near 1.5 per cent. (higher 
than among the fecal streptococci). 
2. Streptococci ferment these carbohydrates in 
a large percentage of the strains: lactose, 74 per 
cent.; saccharose, 68 per cent.; salicin, 77 per 
cent.; inulin, 37 per cent.; mannite, 26 per cent., 
and raffinose, 13 per cent. 
3. The amount of acid is remarkably large 
(highest in saccharose, 8.4 per cent.). 
4. The reaction combinations observed are nu- 
merous, and therefore small: 4 groups of 10 or 
more strains, and 4 of 5 to 9 strains; these in- 
clude about 75 per cent. of the strains. 
5. These reaction groups are apparently not 
correlated with morphological characters. 
6. The high records for acidity are even more 
remarkable when the initial acidity is considered. 
DISCUSSION OF STREPTOCOCCI 
W. L. Holman referred briefly to the Andrade 
indicator—acid fuchsin decolorized by sodium hy- 
drate—as used in the pathological laboratories in 
Pittsburgh. He spoke of the differential media for 
streptococci in use by them, viz., blood agar, lac- 
tose, mannit, salicin and inulin broth and laid 
particular stress on the fermentation or non-fer- 
mentation of the various carbohydrates, believing 
that of greater importance than the exact titration 
of acidity produced. The use of the hemolytic 
test he advocated as of great importance in sepa- 
rating two large groups of the streptococci. 
SCIENCE 
[N. 8. Vou. XXXV. No. 893 
A Study of the Diphtheria Group by the Biometric 
Method: M. E. Morse. 
This study was undertaken for the Boston State 
Hospital at the instance of Dr. E. E. Southward. 
The writer is greatly indebted to Professor C.-E. 
A. Winslow for assistance. 
The characteristics which were chosen as the 
basis of classification were: 
A. Morphology. The cultures of diphtheria ba- 
cilli were grouped as granular, segmented and 
those in which solid and small granular forms 
predominated. 
B. Vigor of growth. 
C. Chromogenesis. 
D. Quantitative determination of acidity in 1 
per cent. dextrose, maltose, glycerin, saccharose 
and dextrin broth. 
EH. Virulence (guinea-pig inoculation). 
F. Toxin production. 
G. Immunity reaction (fixation of complement 
and conglutination). This part of the work is still 
in progress, and will be reported later. 
187 strains of Klebs-Loeffler bacilli, 76 of diph- 
theroids and 23 of Hoffmann’s bacillus have been 
studied. 
RESULTS. I. DIPHTHERIA GROUP 
A study of the relationship between morphology 
and virulence shows that 61 per cent. of the gran- 
ular cultures were virulent, and only 34 per cent. 
of the segmented cultures. The solid and small 
granular cultures were, with one exception, non- 
virulent. 
The group of virulent diphtheria bacilli forms 
more acid in dextrose, maltose and dextrin broth, 
than does the non-virulent group. 
There are forms sharing the characteristics both 
of the Klebs-Loeffler group and the diphtheroids. 
Il. DIPHTHEROID GROUP 
The common diphtheroids found on the human 
body fall into three sub-groups. 
Group A.—The so-called ‘‘ Hoagbacillus.’’ Me- 
dium-sized bacillus with solid, barred and wedge 
forms. On serum, a very heavy glistening salmon- 
pink growth. Ferments dextrose and saccharose 
always, maltose and glycerin infrequently; and 
never dextrin. 
Group B—Morphologically larger and thicker 
than ‘‘Hoagbacillus’’; forms with clear-cut bars 
predominate. On serum, a heavy yellow, dry 
growth. Ferments dextrose, but not saccharose;. 
usually maltose, glycerin frequently. 
