( 583 ) 
After 3 days . the branch was examined; the stain had already 
reached the apex. 
Staining only in the secondary xylem. Against the walls of the 
tracheids there was a thin bine layer, also in the cavities of the 
bordered pits. Tori colourless. Of the medullary rays both the walls 
and the protoplasm dark blue. 
Experiment X. 
Salix spec. 
A living twig was placed with its cut surface in a solution of 
0.1 gram of Saureviolett in 100 c.c. of a 4% formaldehyde solution,. 
After 3 days the stain had penetrated to the apex and the twig 
was examined. 
Staining only in the secondary xylem. The walls of the vessels 
coloured light blue with an indication of a somewhat darker layer 
adjoining the lumen. Tori practically colourless. The medullary ray 
cells, which adjoined the vessels, are coloured blue. 
3. Intetference with the movement of water in a tree-trunk 
by means of deep incisions. 
Experiment XI. 
An experiment with a small willow tree in the Botanic Gardens 
at Groningen showed, that in a trunk in which the transpiration 
current had been largely prevented or perhaps completely cut off 
as a result of transverse incisions on both sides at various heights, 
measures were taken in course of time which ultimately led to a 
complete recovery of this current. 
The experiment was earned out as follows. 
The trunk of the tree, 11 */ a cm. thick, was sawn into transversely 
to slightly beyond the centre at four places, alternately on either 
side of the trunk. The incisions were 22 cm. apart, and the lowest 
was 1.25 Metres from the ground. They were prevented from closing 
up again by the insertion of tin plates, which in future remained 
in position. At these four places the water current was therefore 
irreparably interrupted. 
As the trunk had of course been greatly weakened by this operation 
the tree was supported by four iron wires, which were attached 
high up to the trunk and also to four pegs driven into the ground 
at some distance round the tree. 
