234 ON THE SEEDS OF CERTAIN ALG. 
of the seeds was erroneous, though almost unavoidable. The 
real case seems to be as follows. When the seed separates 
from the matrix upon the field of the microscope, it passes 
into the water in which the plant is immersed. Now if the 
contents of the seed, which are semi-fluid, are of a different 
specific gravity from that of water, a mutual action of 
exosmose and endosmose will immediately take place through 
the epidermis of the seed: the water will pass into the seed 
and part of the fluid matter of the seed will pass out into the 
water; and in consequence of this action, the current pro- 
duced will cause the seed to move about, until an equilibrium 
take place, when the seeds will settle at the bottom and 
begin to vegetate. I have at present had no opportunity of 
establishing the truth of this surmise by experiment, as I 
have found the plant in only one spot. But by varying the 
density of the water by the addition of a weak solution of 
Gum Arabic, I think that there is little doubt that the seed; 
when the motion has just 'subsided and there has not been 
time to fix itself to the bottom of the glass by the sprouting 
roots, would again start into apparent life, and that the 
motion so excited, would continue until an equilibrium was 
again established. The necessary experiments would require 
some care, but to a person accustomed to the use of the 
microscope, there would, I conceive, be no insurmountable 
difficulty. The above reasoning appears so conclusive, that 
even in the absence of actual experiment, most persons will, 
I think, be convinced that the puzzling phaenomena can be 
best accounted for by Dutrochets’ most important discoveries 
on the reciprocal motion of fluids through their membranes. 
