GENERAL CONCLUSIONS. 809 



hourly, in calling into life many forms, by conversion of physical 

 and chemical into vital modes of force, under as many diver- 

 sified conditions of the requisite elements to be so combined. 



( Natural Selection ' leaves the subsequent origin and succession 

 of species to the fortuitous concurrence of outward conditions : 

 6 Derivation ' recognises a purpose in the defined and preordained 

 course, due to innate capacity or power of change, by which 

 iiomogenously-created protozoa have risen to the higher forms of 

 plants and animals. 



The hypothesis of ( derivation ' rests upon conclusions from 

 four great series of inductively established facts, together with a 

 probable result of facts of a fifth class : the hypothesis of ' natural 

 selection' totters on the extension of a conjectural condition, 

 explanatory of extinction to the origination of species, inappli- 

 cable in that extension to the majority of organisms, and not 

 known or observed to apply to the origin of any species. 



427. Epigenesis or Evolution ? -The derivative origin of 

 species, then, being, at present, the most admissible one, and the 

 retrospective survey of such species showing convergence, as time 

 recedes, to more simplified or generalised organisations, analogous 

 to Von Baer's law of individual development, the result to which 

 the suggested train of thought inevitably leads is very analogous 

 in each instance. If to Kosmos or the mundane system has been 

 allotted powers equivalent to the development of the several 

 grades of life, may not the demonstrated series of conversions of 

 force have also included that into the vital form ? 



In the last century, physiologists were divided as to the prin- 

 ciple guiding the work of organic development. 



The ( evolutionists ' contended that the new being pre-existed 

 in a complete state of formation needing only to be vivified by 

 impregnation in order to commence the series of expansions, or 

 disencasings, culminating in the independent individual. 



The ( epigenesists ' held that both the germ and its subse- 

 quent organs were built up of juxtaposed molecules according 

 to the operation of a developmental force, or ' nisus. forma- 

 tivus.' 



Haller maintained the principle of ' evolution,' Buffon that of 

 6 epigenesis.' Hunter, who surpassed all his contemporaries in 

 observations on the formation of the chick, ' thought he could 

 see both principles at work, together with a third.' However, as 

 he limited the f pre-existing entities ' to e the materia vitre uni- 

 versalis ' and the f absorbent faculty,' he would now be classed 

 with the ' epigenesists.' For, he reckoned among the parts newly 



