Drixon—WNote on Supply of Water to Leaves on a Dead Branch. 9 
killed before the injurious effects are noticed also seems to fit in 
with this explanation. 
Or, again, it is conceivable that substances may be exuded 
from the dying cells into the conducting tracts, which obstruct the 
free flow of water upwards, and so prevent an adequate supply 
being transmitted to the leaves. Such substances might themselves 
be quite invisible and elude the most careful examination. 
In order to obtain a clear view of the matter, I repeated some 
of the experiments alluded to above. I used Primula, Chrysan- 
themum, Syringa, Philadelphus, and Cytisus. My results fully 
bore out Ursprung’s accounts of his experiments. If short lengths 
only were killed by the application of steam or of water at 
95°-100° C., the leaves above scarcely suffered. As the length of 
the killed portion was increased, more and more of the leaves 
faded. or example, on a branched specimen of Chrysanthemum 
sinense lengths of 2,3, and 5 cms. were killed on different branches. 
Kach branch carried 6-8 leaves. The uppermost leaves of all 
three branches remained fresh and turgescent during ,the forty 
days the observation was continued. ‘The lower leaves in the case 
of the branches of which 3 and 5 cms. were killed wilted on the 
third day. ‘Two leaves were involved in this injury in the case 
of the branch where 3 ems. were killed, and three leaves where 
5 cms. were killed. 
This observation seems to support the view that the withering 
is due to the presence of a poisonous material, which is supplied in 
proportion to the length of amount of tissue killed. 
If this theory be correct, it should be possible to cause withering 
by supplying water which has passed through a killed branch to 
leaves otherwise normally supplied with water. ‘This was found 
feasible in the following manner :—One branch of a bifurcated 
shoot of Syringa vulgaris was killed by immersion in water at about 
90° C. for ten minutes. After this the dead branch was stripped 
of its leaves, and cold water supplied through it to the leaves sup- 
ported on the uninjured branch. These leaves then drew supplies 
of water from two sources, viz. from the roots, and through the 
dead branch. To facilitate this latter supply a fresh surface was 
occasionally cut on its distal extremity. The length of the dead 
branch in my experiments varied from 30-40 ems. Notwith- 
standing the double supply of water, the leaves on the living 
