OO J. W. SLATER, ESQ., F.C.S., F.E.S., ON 



15. Yet this fact that hfe can exist ouly between certain 

 hniits of tempeiature gives us uo right to infer tliat heat is 

 hfe. We may heat matter — even organic matter — to the 

 most varied degrees, but if we tlioroughly exckide all germs 

 of hfe it remains inert and dead. The manifestations of life 

 and of heat touch each other, but they are not mutually con- 

 vertible. Others — especially quacks — tell us that electricity 

 is life, but they fail to produce any decisive evidence in 

 support of their hypothesis. 



16. It is again said that light is life. In reply, we may be 

 content to point out that nniltitudes of living beings, both 

 plants and animals, exist and nndtiply in absolute darkness, 

 for which, indeed, they seem especially adapted. 



17. We come now to a capital distinction. We may start 

 heat, light, or motion afresh Avhere nothing of the kind has 

 previously existed. We may descend to the furthest accessible 

 point in the Blue .John Cavern at Castleton, where no light 

 has penetrated since the present order of things took its 

 rise. If we have provided ourselves with a box of matches 

 and a candle Ave shall find it quite as easy to strike a 

 match and to light a candle as on the surface of the earth, 

 where the sun's light visits us every day (except in London). 

 Or let us find some place where no electric current is 

 traceable. Yet by rubbing a stick of sealing-wax or a cake 

 of gutta-percha with silk, or catskin, we obtain electric 

 sparks. In short, any of the physical forces can, so to speak, 

 be started afresh. 



18. How. is it with life ? Our great anatomist Hunter said, 

 " all life comes from the egp; " {ovme vivnin c.c ovo), or in other 

 words, thei-e is no life without pre-existuig life, be it in the 

 form of egg, seed, or spore. 



li). Experiments have been made Avithout end to obtain life 

 from inanimate matter. Virgil gives a receipt for creating 

 a swarm of bees from the carcase of a bull. Insects generally 

 Avere suj^posed to arise spontaneously out of dust, Avater, or 

 refuse of any kind. It Avill scarcely be believed that good 

 old Rose], Jan Swannnerdam and other naturalists of the 

 old time had to shoAv how moths, butterflies, beetles, bees, 

 etc., Avere jwoduced from eggs, to trace these creatures 

 through their successive stages of growth and development, 

 and to prove that they no more originate spontaneously than 

 do horses or men. Errors die hard. WhenitAvas shown that 

 insects are procreated by antecedent insects the belie\'ers in 

 spontaneous g(.'neration retreated to more obscure regions. It 



