50 PROGRESS OF SCIENCE IN THE CENTURY. 



when we consider the small number of scientific gen- 

 eralisations which we can venture to describe as of 

 the first magnitude. We begin to count these: The 

 doctrine of the indestructibility of matter, foreseen 

 by Democritus, but for practical, scientific purposes 

 only about a century old dating from Lavoisier; 

 the doctrine of the conservation of energy, with its 

 corollaries of transformability and dissipation; the 

 theory of gravitation, with its far-reaching applica- 

 tions; and the theory of organic evolution which 

 will be linked for ever with the name of Charles 

 Darwin. 



But after we have enumerated these, we begin to 

 hesitate. Are there any others on the same plane, 

 which thoughtful men accept without hesitation and 

 without saving clauses, to lose any of which would 

 spell intellectual disaster? Should we include, for 

 instance, what is grandiloquently called the Law of 

 Biogenesis which states that, so far as we know, 

 every living creature has its parentage in another 

 living creature or in two other living creatures ? This 

 is a big fact, no doubt, but it is hardly more than 

 an empirical fact, and there are many who suppose 

 from forcshadowings which they see that the coming 

 events of the next quarter of a century will con- 

 vince us that this at present unimpeachable conclu- 

 sion will be shown to be fallacious, not in itself per- 

 haps, but in its suggestion of an impassable gulf 

 between the not-living and the living. Or should we 

 include the " biogenetieches Qrundgeaetz" the Re- 

 capitulation Doctrine that the individual develop- 

 ment recapitulates the racial evolution, or that the 

 organism in its becoming climbs up its own genea- 

 logical tree ? but there are many who will agree with 

 Mr. Sedgwick the eminent zoologist of Cam- 



