134 Prof, LeConte on the Correlation of Forces, 
ductive of many beautiful and useful results; but the correlation 
of physical and yital forces, while generally recognized as a pro- 
bable fact, has only been speculated on in a vague and as yet 
unfruitful manner. The science of life is scarcely yet ripe for 
the legitimate extension of this principle over its domain, The 
most elaborate attempt of this kind which I have seen is con- 
tained in the very remarkable and suggestive paper of Dr. Car- 
penter, entitled ‘‘ Mutual Relation of Physical and Vital Forces,” 
and published in the Philosophical Transactions for the year 1850, 
In the present paper I wish simply to present a few thoughts 
which have originated in my own mind in the course of reflec- 
tion on this subject, in the hope that they may proye suggestive 
to others. They have at least the merit of beg uninfluenced 
by the writings of others, and therefore perhaps of presenting 
the subject in a somewhat new light. I sincerely wish I could 
present the matter ina more definite form ; but it is certain that, 
where a subject is not perfectly understood, the attempt to give 
our ideas more definiteness also makes them more questionable. 
We are obliged to be content with a certain vagueness, in the 
hope that by the use of right methods a clearness will come 
after. We must gratefully accept the twilight in the hope that 
it marks the approach of the full light of day. 
There are four planes of material existence which may be re- 
garded as being raised one above the other. The fist and lowest 
is the plane of elementary existence; the second, the plane of 
chemical compounds, or mineral kingdom; third, the plane of 
vegetable existence ; and fourth, of animal existence. Now itis 
apparently impossible for any known force in nature to raise 
matter through all these grades at once. On the contrary, there 
is a special force adapted for the elevation of matter from each 
plane to the plane above. It is the special function of chemical 
affinity to raise matter from plane No. 1 to No, 2. All the 
changes, too, which take place upon plane No. 2 by the mutual 
reactions of bodies situated on that plane, are under the guidance 
and control of this force. It is the special prerogative of the 
force of vegetation—of vegetable life—to lift matter from No. 2 
to No. 3, 2. e. from the condition of mineral matter to the higher 
condition of vegetable matter. All the changes which take place 
upon this plane, the laws of which constitute vegetable physio- 
logy, are under the guidance of this force. Finally, the force of 
animal life, and that alone, enjoys the privilege of lifting mat- 
ter still higher, into the fourth plane, 7. e¢. the plane of animal 
existence. No force in nature can lift from No. 1 to No. 3, or 
from No. 2 to No. 4. Plants cannot feed entirely upon ele- 
mentary matter, nor can animals feed upon mineral matter. The 
reason of this will be seen in the sequel, Thus it seems that 
