CHAP. XIII. 
CIRCULATION OF THE SAP. 
405 
round them, a similar action takes place between them and 
the water in the soil, by means of which the latter is con- 
tinually impelled into their system. Philosophers do not 
seem disposed to admit the legitimacy of Dutrochet’s con- 
clusion, that this transmission takes place by means of galvanic 
agency ; but that the phenomenon is correctly described by 
the ingenious, author, and that it is constantly operating in 
plants, are beyond all dispute. It is by endosmose that vapour 
is absorbed from the atmosphere, and water from the earth ; 
that sap is attracted into fruits by virtue of their greater density ; 
and, probably, that buds are enabled to empty the tissue that 
surrounds them, when they begin to grow. 
But, although endosmose will be found a ready explanation 
of many of the phenomena connected with the ordinary move- 
ment of fluids, it throws no light upon rotation or cyclosis, 
which, so far as we at present know, are motions inexplicable 
upon any principle yet discovered. 
D D 3 
