1864.] Carpunter on Correlation of Physical and Vital Forces. 83 
other, fresh organizing force is constantly being supplied from without 
during the whole period of the exercise of its activity. 
When we look carefully into the question, however, we find that 
what the germ really supplies is not the force, but the directive agency ; 
thus rather resembling the control exercised by the superintendent 
builder who is charged with the working out the design of the architect, 
than the bodily force of the workmen who labour under his guidance 
in the construction of the fabric. The actual constructive force, as 
we learn from an extensive survey of the phenomena of life, is supplied 
by Heat; the influence of which upon the rate of growth and develop- 
ment, both animal and vegetable, is so marked as to have universally 
attracted the attention of Physiologists: who, however, have for the 
most part only recognized in it a vital stimulus that calls forth the 
latent power of the germ, instead of looking upon it as itself furnishing 
the power that does the work. It has been from the narrow limitation 
of the area over which physiological research has been commonly 
prosecuted, that the intimacy of this relationship between Heat and 
the Organizing force has not sooner become apparent. Whilst the 
vital phenomena of Warm-blooded Animals, which possess within 
themselves the means of maintaining a constant temperature, were 
made the sole, or at any rate the chief, objects of study, it was not 
likely that the inquirer would recognize the full influence of external 
heat in accelerating, or of cold in retarding, their functional activity. 
It is only when the survey is extended to Cold-blooded Animals, and 
to Plants, that the immediate and direct relation between Heat and Vital 
Activity, as manifested in the rate of growth and development, or of 
other changes peculiar to the living body, is unmistakably manifested. 
To some of those phenomena which afford the best illustrations of the 
mode in which Heat acts upon the living organism, attention will now 
be directed. 
Commencing with the Vegetable kingdom, we find that the ope- 
ration of Heat as the “motive power,” or dynamical agency, to which 
the phenomena of growth and development are to be referred, is pecu- 
liarly well seen in the process of Germination.. The seed consists 
of an embryo which has already advanced to a certain stage of 
development, and of a store of nutriment laid up as the material for 
its further evolution ; and in the fact that this evolution is carried on 
at the expense of organic compounds already prepared by extrinsic 
agency, until (the store of these being exhausted) the young plant 
is sufficiently far advanced in its development to be able to elaborate 
them for itself, the condition of the germinating embryo resembles 
that of an Animal. Now the seed may remain (under favourable 
circumstances) in a state of absolute inaction during an unlimited 
period. If secluded from the free access of air and moisture, and kept 
at a low temperature, it is removed from all influences that would on 
the one hand occasion its disintegration, or on the other would call it 
into active life. But when again exposed to air and moisture, and 
subjected to a higher temperature, it either germinates or decays, 
according as the embryo it contains has or has not preserved its vital 
endowments—a question which only experiment can resolve. The 
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