J, LeConte on the Correlation of Forces. 315 
y at a given position. How then can growth and animal 
activity goon? The answer to this question is obvious enough 
when we recollect the nature of the food of animals. Animals 
it is well known cannot feed upon mineral matter but only on 
food already organized, at least up to the vegetable condition. 
But when decomposition takes place, the animal matter returns 
no longer to the vegetable condition from which it was immedi- 
ately raised, but to the mineral condition. It is decomposed into 
J, HO and urea, This last substance though not strictly a 
mineral substance is far below the condition of vegetable matter. 
hus it is evident that a given quantity of matter falling 
soreer quantity of matter from the vegetable to the animal condi- 
7 
is view of the case we see at once the absolute necessity 
that the food of animals should be organized. Lee the princi 
of conservation of force, growth and animal activity, in a 
Word, animal life, would otherwise be impossible. =| 
It follows also from the above, that the higher the ae 
