BACTERIAL DISEASE OF TOBACCO. 439 
this view I have since satisfied myself. The writer has seen the 
same thing in the wood of young shoots of the mulberry attacked 
by Bact. mort. Here the stimulus to growth appears to be due 
to poisonous products absorbed by the vessels of the plant in 
advance of the movement of the bacteria. This is quite in accord 
with what we know of the action of many poisons, minute doses 
stimulating and larger doses destroying.” 
HK. Smith figures a potato shoot inoculated with a non- 
virulent culture of Bact. solanacearum Va. The inoculated 
stem is swollen. 
I have not come across any reference to bacterial infec- 
tion following an attack of Peronospora hyoscyami. H. 
Smith, however, gives a translation of a paper by Dr. 
Hunger on the Dutch Eastern Diseases of Tobacco. 
Dr. Hunger describes the symptoms of the disease, which 
are very similar to the disease found in New South Wales 
so far as the effect upon the vascular system is concerned, 
but I have not observed the production of such complete 
wilting of the leaves of the mature plant as he describes. 
He concludes :— 
“The inclination to this formation of tyloses is caused by a 
bacterium (Sacillus solanacearum Smith), which by means of 
many sorts of external wounds is given an opportunity to enter 
into the interior of the plant. When once entered into the xylem 
vessels the vessel wall is through them partially absorbed, so that 
the above mentioned tyloses are formed. The slime-disease 
described here is altogether a secondary phenomenon, which is 
made possible by external wounds. 
“In by far the most cases injury of the plant takes place either 
on the root or on the stem concealed underground. In the latter 
case | mean the stem part which has been covered with earth by 
heaping up the ground. The woundings may be due to many causes. 
In the first place should be mentioned wounds due to plant and 
animal parasites, Among the first named I reckon chiefly the 
parasitic moulds, especially Phytophthora nicotiane. 
