298 
Maugham. — On the Mechanism of 
Finally, if the adsorbing material were present either in very high con- 
centration, so that the particles were only separated from one another by an 
infinitesimally thin film of solvent, or were actually continuous, forming 
a meshwork, as is probably the case in a gel, the distance to be traversed 
before coming into contact with a surface in which concentration could occur 
would be reduced still more. 
The rate of transference would then approximate to that at which 
condensation on the surface of the adsorbing phase would occur, that is, in 
all probability it would be extremely rapid . 1 
The specific concentration relations existing between the particular 
substances concerned at the adsorbing surface and in the layer of solvent 
immediately in contact with it would, of course, obtain, so that there would 
be a wave of adjustment to a state of equilibrium, the rate of propagation 
of which would depend on the rate of spreading of the sugar over the 
adsorbing materials. 
So far, the process has been dealt with only partially, and has been 
treated as if the sugar formed in the photosynthetic cells passed onwards into 
protoplasm and solvent containing no sugar. This is simply for purposes of 
description, and is hardly likely to represent a state of affairs ever occurring 
in the plant. 
Actually the process must be more complex, although conditioned by 
the principles enunciated above. 
It is possible now to pursue the matter somewhat farther. 
In the case of a single cell, such as a unicellular green alga, the sugar 
would diffuse into the vacuole, and the concentration there and at the 
surface of the protoplasmic constituents would tend to reach a state of 
equilibrium, which, however, would be continually disturbed by the metabolic 
changes incidental to growth and reproduction. 
In a filament such as Spirogyra the conditions would probably be much 
the same, since the plant is simply a series of equivalent cells all under 
practically identical conditions. 
With such a plant as Laminaria , however, the existence of tissue 
differentiation and of localized meristematic regions adds complications. 
Here the carbohydrates are produced in those of the outer cell layers into 
which light penetrates. The inner layers, being shaded, assume other 
functions. 
The soluble assimilates would travel as above described in the cells 
producing them. But the protoplasm of each cell is continuous with that 
of its neighbour by means of the connecting-threads in the walls . 2 
The solutes have an unbroken protoplasmatic pathway throughout the 
1 Cf. Bayliss, l.c., pp. 56 and 61 . 
2 Sykes (1908). It is here assumed that a real continuity of protoplasm exists, although the 
exact nature of * median nodules 1 has not been ascertained. 
