152 Dale.— A Bacterial Disease of Potato Leaves. 
Bacillus Solanacearum 
(Smith). 
Bacillus melanogenes 
(Pethy bridge). 
Bacillus Tubifex , n. sp. 
13 . 
14. 
15 - 
16. 
17 . 
38. 
IP- 
20 . 
23 - 
24. 
2 5 - 
26. 
27 - 
Growth on gelatine not leaf- 
like. 
Does not liquefy gelatine. 
No gas in potato or in media 
with various sugars. 
No acid formed in potato or 
glucose solutions containing 
nitrogenous substances. 
Goes through bundles into 
tuber, where cavities are 
formed. 
No spores. 
Sluggishly motile, active in 
young cultures. 
Bacilli in short rods. 
Bacilli blocking up vessels of 
host plant. At first only in 
the vascular tissues, but 
later in parenchyma. 
Infection through wounds 
caused by insects, &c. 
Injury caused chiefly by the 
blocking up of the vessels. 
Almost entirely confined to 
stems and tubers. 
Causes wilting and browning 
of foliage and stems, 
Liquefies gelatine fairly ra- 
pidly. Begins the second 
day in gelatine stab. 
Slight formation of gas with 
sugar. 
Forms acid. 
In subaerial stems. 
No spores. 
Actively motile. Peritri- 
chous flagellae. 
Bacilli often in pairs or in 
threes or in long chains. 
Vary little in size. 1.3 to 
i-8 x 0.9^. Chains up to 
20 or 70 /x. 5 to 10 peri- 
drichous flagella. 
In vascular tissue of the stem 
of the potato plant. 
Infection chiefly from the 
tuber, the organism grow- 
ing up the stem through the 
vascular tissues.. 
Injury chiefly as in B. Solana- 
cearum. 
Causes blackening of stems, 
withering of leaves,, and rot- 
ting of tubers. 
On gelatine plates forms mi- 
nute white dots. Liquefac- 
tion after the second day. 
On agar white dots are formed 
in 48 hours as in gelatine. 
Surface covered with grey- 
ish white growth, somewhat 
crenated along the margin. 
Not vigorous in beef extract 
peptone. 
In cane-sugar broth gas and 
acid produced. 
Active growth in potato juice. 
Forms circular colonies on 
gelatine plates. 
Liquefies gelatine rather 
slowly. 
Forms large bubbles of gas 
on potato and in cane-sugar 
and peptone in gelatine. 
Forms acid in cane-sugar and 
peptone in gelatine. 
Not found in tuber nor in 
stems, but only in leaves, 
especially in the veins but 
not in the vessels. 
Spores formed readily and 
plentifully in a few days on 
potato tuber. 
Actively motile in liquid 
media. 
Bacilli in short rods and long 
filaments of all lengths ac- 
cording to conditions of 
growth, nature of medium, 
age of culture, &c. Flagellate. 
Average size 3-7 x 1*23 /*, 
minimum 2qxo-8fi, maxi- 
mum 5 x 1.7 \x. 
Bacilli' in and between the 
cells of the parenchyma and 
phloem. Seldom in the 
vessels and only in later 
stages. 
Infection through uninjured 
epidermis by means of in- 
fection tubes, as in the 
nodules of certain legu- 
minous plants. 
Injury caused by disorganiza- 
tion of tissues due to passage 
of infection tube, and by 
lesions in cells filled with 
Bacteria. Also indirectly by 
the using up of the products 
of metabolism. Almost 
confined to leaves. 
Causes withering and drying 
of leaves from outside in- 
wards. Often accompanied 
by ‘ curl but not always. 
White dots on second day on 
gelatine plates and along 
line of stab. Liquefies gela- 
tine. 
On agar plates dots as on 
gelatine. In stab cultures 
forms wavy films along the 
line of stab. 
Rapid growth in ‘Lemco’. 
In cane -sugar-peptone gela- 
tine gas and acid produced. 
Active growth in liquid ex- 
tract of potato tuber. 
