41 8 Dixon and Joly.—The Path of 
experiment. The vessel into which the branch dips contains 
mercury heated from beneath. A glass tube surrounds the 
branch, the space between branch and glass being filled with 
mercury. To resist the tension of the vapour evolved from the 
surface of the wood at this temperature it was necessary to 
bind the stick into the tube with air-tight rubber rings over- 
laid with wire. The following experiment was made : — - 
A small branch of Taxus haccata , 24 cm. long, having 
a woody cylinder of $-6 mm. in diameter and being composed 
of nine annual rings, was kept jacketed with mercury at 125 0 - 
130° for eight minutes, while its basal end was attached to an 
air-pump so that the atmospheric pressure acted from the 
distal end through the branch. The water was then replaced 
by a strong solution of eosin, and the whole, still kept at - 
i25°-i30°, was left for two hours. Then the experiment was 
broken off. The eosin being first removed, the surface to 
which it had been applied was re-cut and dried. The branch 
was then detached from the air-pump and allowed to cool. 
On microscopic examination it was found that the eosin- 
solution had passed 22 cm. up the stick, and at this height 
was seen in cross-section as two irregular patches occupying 
quadrants in the seventh and eighth rings. The walls of 
these were uniformly coloured. At the level of the mercury 
jacket and throughout the 7 cm., where the branch was im- 
mersed in mercury, the colouring was most intense in the 
limiting membranes. At the end where the eosin was applied 
the walls were scarcely coloured except those adjoining the 
medullary rays and immediately round the bordered pits. 
The simplest interpretation of these results is that the 
coloured water moved in the wall while the lumen was 
occupied with vapour ; the intenser colouration of the limiting 
membrane is strongly in support of this view, for it is very 
probable that for some distance from its surface the wall was 
so far choked with vapour as to impede the motion of 
a liquid. 
These experiments then, so far as they go, are in perfect 
agreement with the previous set in which the lumina are 
