228 
Notice of Book. 
to raise a fluid to a height of 20 metres. Thus the living- elements 
do not take part in the raising of water within the plant ; they may, 
however, excite “ bleeding ” by pumping additional fluid into vessels 
which are already full/ 
Other striking experiments proved that water can be conducted 
through stems which have been killed for a great length by immersion 
in water at a temperature of 90° C. An ascent of liquid took place 
in spite of the fact that the transpiring organs were at a height of 
much more than 10 metres above the place of absorption, and separ- 
ated from it by more than 10 metres of dead stem (p. 647). 
Similar results were attained with plants which were completely 
dead, the only conditions necessary being that the dead tissues should 
be sufficiently injected with water, and their cell-walls sufficiently 
saturated (p. 663). 
The author further proved that water can be raised by the plant 
without the help of atmospheric pressure. In these experiments the 
absorbing plants raised a column of mercury 67 cm. in height (in the 
case of Dicotyledons), and 70 cm. high, in the case of a Conifer. These 
mercury columns, with the addition of the column of water in the 
branch itself, were more than sufficient to counter-balance the atmo- 
spheric pressures (p. 791). 
This review has already reached an extreme length, and it is 
impossible to notice the innumerable other points of interest pre- 
sented by the physiological part of the book. The attention of the 
reader may however be specially called to the passages on the function 
of bordered pits (which are particularly adapted to keeping out the air 
from empty tracheae), on absorption from the soil (in which a quali- 
tative power of choice is again claimed for the roots), and on the 
function of the tracheae in conducting assimilated food. Here the 
striking fact is brought forward, that in certain cases of £ ringing ’ the 
xylem is able completely to replace the phloem in the conduction of 
nitrogenous and other organic food-substances to developing organs. 
This does not, however, affect the fact that under normal conditions 
this conducting function belongs to the phloem. 
In a section on annual rings the author shows that their formation 
is an inherited character, but that the degree of differentiation between 
spring- and autumn-wood depends on the intensity of the ascending 
water-current, for which channels have to be provided, and which 
acts as a stimulus on the developing cambial cells. 
