370 
Journal of Agricultural Research voi. xxm, no. 5 
Table) II .—Acidity of Lewis's geranium leaf spot organism 
Medium. 
Fuller’s 
scale. 
Increase in 
acidity. 
Saccharose. 
Uninoculated. 
Inoculated 21 days.. 
Uninoculated. 
Inoculated 21 days.. 
Uninoculated. 
Inoculated 21 days.. 
Uninoculated. 
Inoculated 21 days.. 
Uninoculated. 
Inoculated 21 days.. 
+ 10 
+ 18 
+ IO 
1 8 
Dextrose. 
1 7 
Maltose. 
+ 17 
+8 
+ 12 
+8 
+ 16 
+10 
J 1 
1 4 
Lactose. 
J 4 
1 8 
Glycerine. 
J 
1 6 
+16 
J 
In neutral beef bouillon acidulated to +22 with hydrochloric acid 
there is no growth. This test was made because it was not stated 
in Mr. Lewis's article what his foundation beef bouillon was. In the 
same neutral bouillon acidulated with malic acid there is growth at + 10 
(P H 7.1) ; none at -f 19.5 (Ph 6.5). Acidulated with lactic acid, there is 
growth at +9 (P H 7.1). There is none at +22 (P H 6.1). 
Thinking that perhaps Mr. Lewis had used beef extract and Witte's 
peptone instead of beef infusion and Difco peptone, tests were made 
using beef extract media with these acids and with tartaric acid added to 
the list. 
There was growth in the extract (uncorrected 4- 7) made neutral and 
then acidulated with malic acid to +10 (P H 6.2); no growth in +21 
(Ph 4-9)- 
With lactic acid there was growth in +9 (P H 6.4); none in +18 
(Ph 4-9)- 
With tartaric acid there was growth in + 9 (P H 6.4); none in + 20 
(Ph 4-7). 
With hydrochloric acid there was no growth at +21 (P H 4.0). 
In peptonized beef juice made alkaline with sodium hydroxid, growth 
takes place to —6 (P H 8.7). No growth takes place at —9 (P H 9.1). 
With peptonized extract of beef, the titration of which was + 7 reduced 
with sodium hydroxid to — 2, — 6.5, and — 13.5, there was growth at — 2 
and —6.5 (P H 8.4 and 9.4, respectively). 
In a long series of tests with peptone-beef bouillon in which the beef 
juice was used, the titration range of the organism was found to be — 6 
to +28 and the P H range 8.7 to 5.7. 
Mr. Lewis's notes are as follows regarding sensitiveness to acids and 
alkalies: 
The organism grows best in culture media that are acidulated to +15 or +20 with 
HC 1 . Growth does not occur at +40 and is retarded above +30. The same degree 
of acidity is not tolerated when malic, tartaric or lactic acids are employed. The 
growth in +8.5 lactic acid appears to be about the optimum for this acid, and the 
maximum is lower than for hydrochloric. Growth fails at +30 tartaric and malic. 
In media titrated to —10 with normal NaOH the growth is retarded, while no 
growth occurs at —20. In neutral bouillon growth proceeds more slowly than in 
-f-10 or 4-20.' 
