20 Absorption of Water by the Leaves of Plants. (January, 
of the Perigenesis of the plastidule, and with it the theory of — 
dynamical differentiation—because the latter is no longer a © 
hypothesis—forever relegates teleological doctrines to the cate- — 
gory of extinct ideas. No matter how much our ideas may need ~ 
to undergo modification, some similar hypothesis must eventually 
hold sway over the minds of biological thinkers, as the facts of 
science point in that direction and in no other. 
It has been suggested in conversation by my friend Dr. A. J 
Parker, of this city, that the assumption of the plastidule as the 
ultimate physical unit of living matter was unnecessary, as it con- 
sisted merely in naming the protoplasm molecule, and it must be 
admitted that this view of the case is not without reason. Prof. 
Haeckel, it is to be supposed, however, adopted this name merely | 
to distinguish his own provisional hypothesis from that of his 
acknowledged master. The word plastidule is a diminutive of the x 
current word plastid, which is synonymous with cell, and there- _ 
for, implies and correctly, too, that the plastids are aggregates of — 
varying numbers of plastidules, which are for physical reasons the — 
smallest possible or conceivable units of living matter, of which 
even the most minute gemme or, budding cells are composed. 
ate : 
ABSORPTION OF WATER BY THE LEAVES OF | 
| PLANTS. 
BY ALFRED W. BENNETT, M.A., B-S., F.L.S. 
~LTHOUGH gardeners universally maintain that growing 4 
leaves, both in the liquid and the gaseous form, in addition to the 
The first recorded experiment, of any value on the subject, was 
about the year 1731 by Hales, as described in his “ Vegetable 
Statistics; the conclusion to which he came being that “it is 
very probable that =e and dew are imbibed by vegetables, espe- 
cially i in dry seasons.” This result was confirmed by Bonnet in ~ 
ee | 17 33- A century later, however, in 1857, Duchartre,experimenting 
-on the absorptive power of plants, came, after considerable waver- _ 
ing, to the conclusion that rain and dew are not absorbed by the 
leaves of plants. This opinion has been, with but little exception, 
held by all physiologists during the last twenty years, notably by 
