766 THE POPULAR SCIENCE MONTHLY. 



The evidence, then, would seem conclusive that, since the proto- 

 plasm of the animal and the vegetable kingdoms is identical, the for- 

 mer in all cases being derived from the latter, the animal as such 

 neither produces nor vitalizes any protoplasm. Two inferences seem 

 naturally to follow from this conclusion : 1. That all the properties of 

 animal protoplasm, and of the animal organism of which it constitutes 

 the essential part, must have a previous existence in the plant ; 2. That 

 hence the solution of the life-question in the Myxomycetes will solve 

 the life-problem for the highest vertebrate. 



Another consideration which must not be left out of the account in 

 any discussion of the life-question is the potent influence of environ- 

 ment. Ordinary examples of this influence pass before our eyes every 

 day. Heat necessitates the germination of the seed, and light causes 

 the plant to grow. Gravity obliges its root to grow downward and its 

 stem to ascend. Certain sensations from without excite inevitably 

 muscular contraction ; and a ludicrous idea may provoke laughter in 

 defiance of the will. Epidemic and epizootic diseases show the de- 

 pendence of function upon external conditions, and the germ theory 

 demonstrates the utter disproportionality of the cause to the effect. 

 The remarkable similarity in the periodicity observed between sun- 

 spots and the weather has been extended to include the appearance of 

 locusts and the advent of the plague. Even the body politic feels its 

 influence, Jevons having established a coincident periodicity for com- 

 mercial crises. 



The modern theory of energy, however, puts this influence in a 

 still stronger light. As defined hitherto, energy is either motion or 

 position ; is kinetic or potential. Energy of position derives its value 

 obviously from the fact that in virtue of attraction it may become 

 energy of motion. But attraction implies action at a distance ; and 

 action at a distance implies that matter may act where it is not. This 

 of course is impossible ; and hence action at a distance, and with it 

 attraction and potential energy, are disappearing from the language 

 of science. But what conception is it which is taking its place ? By 

 what action does the sun hold our earth in its orbit ? The answer is 

 to be found in the properties of the ether which fills all space. The 

 existence of this ether, the phenomena of light and electricity abun- 

 dantly prove. While so tenuous that astronomy has been taxed to 

 prove that it exerts an appreciable resistance upon the least of the 

 celestial bodies, its elasticity is such that it transmits a compression 

 with a wellnigh infinite velocity. On the one hand, Thomson has 

 determined its inferior limit, and finds that a cubic mile of it would 

 weigh only one thousand millionth of a pound ; on the other, Herschel 

 has calculated that, if an amount of it equal in weight to a cubic inch 

 of air be inclosed in a cubic inch of space, its reaction outward would 

 be upward of seventeen billions of pounds. Instead of being repre- 

 sented, as is our air, by the pressure of an homogeneous atmosphere 



