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according to this theory, is either a portion of the material 
world absorbed by another portion, or a portion of the material 
absorbed by the living. Can material acting upon material, 
generate anything but material ? Whatever may be the com- 
binations of natural products, and whether they absorb sun- 
force or any other material motion, the experimentalist is 
dealing with nothing but the inorganic, yet expects the elimi- 
nation of life. But if sun-heat be absorbed by, and become 
latent in, an object not inorganic— in vegetable, for instance — 
and so conveyed to animal in its food, we have now matter 
acting on life. How can that matter perform any function of 
life, since life already was ? It cannot be pretended that 
sun-heat is life ; for it is said to be imbibed by life : it may, 
therefore, be a part of living tissue, but not itself producing 
that tissue. 
A great deal has lately been made of this absorption of sun- 
force, either by matter or organism, and its subsequent 
liberation. Bub two pieces of ice together, and they will be 
melted by the generation of heat during the process ; or, 
rather, according to the doctrine of latent heat, by the libera- 
tion of formerly stored up sun-force. That heat is an accom- 
paniment of friction, no one doubts. Does it necessarily follow 
it should have been previously imbibed, whether directly from 
the sun, or indirectly through former metamorphoses ? We 
are assured that such is the fact ; that sun-heat has been 
received and become latent till the application of the test for 
reproducing it. Granting this to be, we can, from no struc- 
tural studies whatever, gain a knowledge of the introduction 
of heat into bodies, any more than by dissection of the brain, 
we can track thought to its home ; and by looking on the 
cerebral convolutions, determine their revelations. 
According to the sun-force theory, organisms must be per- 
petually giving it off as long as life endures ; continual re- 
absorption going on to supply the waste. And this, we are 
told, is accomplished by the heat which had been rendered 
latent in the food we consume and in the air we breathe ; the 
powers of the animal, so far as sun-force is concerned, must 
therefore be proportioned to its appetite and capacity of 
lungs. 
It seems then to follow, from their own arguments, that all 
living things, if not exactly children of the sun, are greatly 
dependent on sun-force, as one of the conditions of life 
accompanying constructive organization ; other material 
combinations being further conditions of life. It results, 
therefore, that neither separately nor conjointly, can these 
be the life, or produce it ; nor of themselves manifest inde- 
