Aug. 26,1918 Susceptibility and Resistance to Citrus-Canker 
343 
In contrast to the fine condition of the oval kumquat, the plants (20 inches) are 
seedlings with a single shoot and have remained in a more or less dormant condition 
throughout the experiments. Consequently no canker has developed on these 
plants, even at the punctures, showing that the condition of the plants is of extreme 
importance in inoculation work of this character, and that unless all of the plants 
are in vigorous growing condition, no comparisons can be made. Inoculations with 
this kumquat will be repeated with more vigorous plants, and no doubt they will 
be found susceptible to some extent. 
Fortunella Hindsii (Oliver) Swingle (Sclerostylis Hindsii Champ,; Atalantia Hindsii 
Oliver). Hongkong wild kumquat (CPB 11046C, seedlings), I, II. 
This kumquat, which differs in some respects from the others, grows wild on the 
dry hills about Hongkong. Unfortunately no clear and concise test was made of this 
species, because the plants (12 inches) have remained in a more or less dormant condi¬ 
tion throughout the experiments. Citrus-canker spots appeared early on the plant 
in the first experiment at four punctures on an old, tough leaf. Judging from the size 
and character of these spots, it will prove more susceptible than the oval kumquat. 
Inoculations will be repeated on more vigorous plants. 
Microcitrus australasica (Muell.) Swingle ( Citrus ausiralasica Muell.). Finger lime 
(CPB 7600 and 7600B, cuttings and seedling), I, II, and II. 
A small tree, native to the mountains of New South Wales and Queensland, 
Australia. 
No spots of any kind have developed on the leaves. 
Microcitrus australasica var. sanguinea Swingle (CPB 7775B, cutting), II. 
A blood red variety of M. australasica. 
No spots have appeared on the leaves. 
Microcitrus Garrowayi (Bail.) Swingle ( Citrus Garrowayi Bail.). Garroway’s finger 
lime (CPB 11008, cuttings), I, II. 
A plant similar to M. australasica and native to the same region. 
A few oily swellings have developed which yielded negative results on making 
isolations. 
Microcitrus australis (Planch.) Swingle ( Citrus australis Planch.). Dooja (CPB 7307 
and 7427, cutting and seedling), I, II. 
An Australian lime, much more vigorous than the others, growing in the subtropical 
coastal forests of New South Wales and Queensland, The first plant (8 inches) devel¬ 
oped very slowly and did not produce much new foliage. The second plant (32 
inches), however', developed a large amount of new growth and has been in splendid 
condition for infection. Numerous Citrus-canker spots appeared on the leaves, twigs, 
and thorns of this plant one month after inoculation. Since that time canker has 
caused rapid defoliation of the plant, so that 50 per cent of the leaves have fallen. 
The plant is very susceptible. No doubt the other species of Microcitrus will prove 
susceptible to some extent when the right conditions are met with. 
The spots (PI. 53, G.) produced are numerous, small, occasionally 1 mm. in diameter, 
of a chocolate-brown color, raised, corky, and pushing through to the upper surface. 
Little or no oily outline is visible, while the yellow zone is wide and very distinct. 
Defoliation was rapid, and twig and thorn infection severe. The plant is quite sus¬ 
ceptible, ranking slightly below Poncirus trifoliata. 
From the results, up to March 1, 1918, of the inoculations in the 
greenhouse on the wild relatives of citrus, it appears that Citrus-canker 
is apparently limited to those plants having edible fruits with stalked 
