1879. ] A Speculation on Protoplasm. 425 
be correct, the establishment thus of the existence of several differ- 
ent independent lines of force renders the existence of a geo- 
metrically constructed organic unit at least probable. 
Why these smallest organic molecules do not construct the 
perfected product on their own model, while the analogous crys- 
talline molecules do, is a problem for future solution. 
If the sarcode or protoplasm be susceptible of slight chemi- 
cal changes, and in fact suffers such changes without losing the 
power to fulfill its function of repairing waste tissue, then in the 
progress of the decay of worlds, and the changes of external 
conditions consequent upon it, Darwin’s law of survival must 
inevitably be felt where an accidental alteration of the substance 
of the sarcode and the resulting changes impressed: upon the 
structure enabled one animal to live where others perished. The 
formation of more combustible compounds, and the increase of 
the capacity of alimentation, for instance, might balance the ten- 
dency of the atmosphere of a cooling earth to depress the tem- 
perature of the blood below the living point. But why should it 
only exert its recuperative energy in the direction of maintaining 
the present condition of things? An amount of plasticity equal to 
this need is quite capable of changing the conditions of life them- 
selves, and instead of rendering it possible for maz to exist with 
blood at 99° Fahr., in an arctic world; to manufacture of man and 
his terrestrial companions, beings to whom that temperature 
would be normal and salutary. 
To a limited extent it seems as though we were justified in 
accepting a difference of this kind in our present organic na- 
ture. How else than by a sarcode of different chemical consti- 
tution are the physical differences of race to be accounted for? 
How, indeed, is evolution to be accounted for according to the 
Darwinian explanation ? 
And if the change to varieties is thus produced, why not to spe- 
cies, genera, families, groups, orders, classes, sub-kingdoms ;— 
why is it not possible that the very kingdoms of life and the 
forms peculiar to them may be altered in this way to suit the 
gradually changing external conditions of nature? The prejudice 
in our minds against the possibility of any living thing existing 
on the surface of the sun is based upon various conditions there, 
which in our experience are inconsistent with life. Amongst 
others may be mentioned, that to the best of our knowledge, Ist, 
. 
