114 ANNUAL OF SCIENTIFIC DISCOVERY. 



organize, we consume ; and thus it is that the same material oscillates 

 back and forth, now a part of a plant, now a part of an animal, now 

 in the air, and now in a plant again. It runs through cycle after cycle, 

 ever returning to the point whence it set out, and ever setting out 



again. 



We are not, then, the special or exclusive proprietors of the sub- 

 stance of which we are composed. Equally may the plant, and equal- 

 ly any animal, no matter how humble in the scale of life it may be, lay 

 claim to it. We are bound to them and they to us by an indissoluble 

 tie. 



If that is the lesson we derive from our best knowledge of the 

 mutations that happen to the plastic material which the hand of nature 

 fashions into so many beautiful forms, we are brought to the same 

 conclusion bv a consideration of the physical forces with which she 



/ J_ *> 



invigorates it, the heat possessed by the different animal tribes, cold- 

 blooded or hot, in their special degree, the chemical affinities and the 

 electrical powers that preside over all the thousand combinations and 

 decompositions perpetually occurring in the inmost recesses of the 

 economy. "In a waterfall which maintains its place and appearance 

 unchanged for many years, the constituent portions that have been 

 precipitated headlong glide finally and forever away. For the trans?- 

 tory matter to exhibit a permanent form it is necessary that there 

 should be a perpetual supply and also a perpetual removal. So long 

 as the jutting ledge over which the waters rusli and the broken gulf 

 below that receives them remain unchanged, the cataract presents 

 the same appearance. But variations in them mold it into a new 

 shape. Its color changes with a clear or cloudy sky. The rainbow 

 seen in its spray disappears when the beams of the sun are withdrawn. 

 So in that collection of substance which constitutes an animal, what- 

 ever may be its position high or low in the realm of life, there is a 

 perpetual introduction of new material and a perpetual departure of 

 the old. It is a form rather than an individual that we see. Its 

 permanence depends altogether on the permanence of the external 

 conditions. If they change it also changes, and a new form is the 

 result. 1 ' 



An animal is, therefore, a form, through which material substance 

 is visibly passing, and suffering transmutation into new products. In 

 that act of transmutation, force is disengaged. That which we call 

 its life is the display of the manner in which the force thus disengaged 

 is expended. 



A scientific examination of animal life must include two primary 

 facts. It must consider whence and in what manner the stream of ma- 

 terial substance has been derived, in what manner and whither it 

 passes away, and since force cannot be created from nothing, and is 

 in its very nature indestructible, it must determine from what source 

 that which i.s displayed by animals has been obtained, in what manner 

 it is employed, and what disposal is made of it eventually. The force 

 thus expended is originally derived from the sun. Plants are the 

 intermedium for its conveyance. For the sake of obtaining it, we use 

 them as food. And here again remarks apply similar to those we have 

 made respei ting mute-rial substance. The correlation and conserva- 

 tion of force holds goo,!. The'asscrtion of the great Spanish Moham- 



