20, 3 McLean and Lee: The Citrus-canker Organism 317 
with the mercury at 19 and 20 centimeters and above were 
reached, 
For comparison with these results Tables 3 and 4 of grape- 
fruit and pummelo tests are given. 
TABLE. 4.—Showing the results of immersing leaves of a pummelo seed- 
ling tree in an infusion of Pseudomonas citri and exerting graduated 
degrees of pressure upon such leaves. Incubation period twenty-seven 
days. 
No. of 
Pressure.| Twig No. ge tip Condition of leaves. Cankers. 
twig. 
cm. 
0.0 1 Dt a WOON BLOWN atc ee Numerous. 
0.0 2 hi} ONG fourth growit ose ct Sas None. 
0.0 3 4| Two-thirds grown e ----| Numerous. 
0.0 4 Ul QrOW Yee ea oh ee ee od Several. 
0.0 5 4 | Three-fourths grown.__._..._..._-__---- Kose cube Numerous, 
3.1 2 0 | Malt grOWii Gi a ee aes ae Do. 
4.7 2 Bt cscs OOS ASR eens eeu oe bac sc cenietan dae Do. 
5.0 8 1 | One-third grown .._- Do. 
5.2 4 Die Ol BTOWI osc sc i aco caanuselruedcakeanee Do. 
7.3 2 TE A WI i i Do. 
7.6 4 4 Three-fourths grown._..__.......--.---- eee Do. 
7.8 3 2) Half grown sete Do. 
8.8 5 6 } Pull grownsc. sesh si ees wen ctid te weswne scenes ces Do. 
9.6 8 8 | Half grown asl ..--| Leaf fallen, 
9.6 1 4 | Two-thirds grown Sigs ..--| Numerous. 
10.0 4 2) mall grown 22.c 2a Do. 
10.0 5 6 | Three-fourths grown eae Do. 
10.2 4 3 | Two-thirds grown wale 7 
10.9 5 3 do... aire Numerous. 
a11.2 1 sd pamee ees Do. 
aji.9 5 2 GG ch dk: innit scons costs eened cesta Do. 
912.3 4 1 | Half grown alia Do. 
a13.0 5 1 | Two-thirds grown.-. Do, 
13.3 8 Fat M6355: Leaf fallen 
17.0 1 1| Half grown we Numerous. 
35.0 1 8 | Two-thirds grown.....-. : tang Do. 
§ Injected. 
Whereas in the Szinkom mandarin orange infection of leaves 
took place mainly at pressures recorded by 10 centimeters of 
mercury and higher, in the tests of grapefruit leaves shown 
in Table 3 infection took place readily, either without pressure 
or at very low pressures. Five of the seven negative results 
with grapefruit were on twig 1, which was on a separate tree 
and was apparently more resistant than the others. Although 
the results are not so consistent as in Table 1, it is very evident 
that abundant infection took place at much lower pressures 
