1896.] Water Current in Cucumber Plants. 561 
water necessary for its use through 33 cm. of dead stem. 
Probably if air could be prevented from gradually passing 
through the shriveled stem into these water carrying vessels 
and interfering with the normal condition of things the plant 
might continue to draw its water through a dead stem almost 
indefinitely." 
5. Tue RESULT oF PARASITIC PLUGGING OF THE VESSELS. 
From these experiments and those upon the cucumber wilt, 
which I have published elsewhere, it follows that the down- 
ward path of Bacillus tracheiphilus from the inoculated leaf 
blade into the stem of the cucumber (for an account of this 
disease see Centr. f. Bakt. u. Par. Allg. I, No. 9-10, 1895) is ex- 
actly that made use of by the ascending water current, just as 
I stated it to be at the Brooklyn meeting” of the A. A. A.S., 
and the general wilt of the foliage may be explained, first, by 
a functional disturbance, due to the more or less complete 
clogging of the lumina of the spiral vessels with countless 
millions of these bacteria which thrive in the alkaline fluid of 
the vessels, and, second, by a structural disturbance, due to 
the breaking down (dissolving) of the walls of these spirals 
and the flooding out and subsequent growth of the bacteria in 
the surrounding parenchyma and in the pitted vessels, accom- 
panied, of course, by the more or less free entrance of air into 
the spirals. It is probable, although not enough examinations 
have yet been made to render this certain, that no leaf wilts 
from secondary infection until the water carrying spirals in 
its petiole have become clogged by the bacillus, i. e., that the 
wilt of the leaf is not induced by the partial clogging of the 
vessels farther down inthestem. This is the more likely, first, 
from the fact that there is always a progressive wilt, leaf after 
leaf, beginning with the ones nearest the point of infection 
and moving both ways therefrom, and, second, from the fact 
that very rarely are all of the pitted vessels filled, so that 
water lifted up from the roots has always the opportunity to 
1 Those who wish to follow these subjects may consult the above mentioned 
work by Strasburger, pp. 510-936, where many interesting experiments are 
detailed. 
39 
