Active Causes of Organic Evolution 203 



that at least some phenomena of reproduction have a far-reach- 

 ing value, and even dynamic significance. A brief considera- 

 tion of some of the more important facts will alone be attempted 

 here. i\.nd in this the history of asexual spore cells, as well 

 as sexual gamete cells, will shortly be included. Ample reason 

 for such a course is given on pp. ^5^-256. 



The formation amongst algse of akinetes, aplanospores, and 

 swarmspores often occurs at exact seasonal periods, and rep- 

 resents phases of energy transformation, of cell metabolism, 

 and of species dissemination that are alike vital and helpful 

 to each organism, but which in no way fall under heredity, 

 environment, proenvironment, or selection, though more or 

 less influenced by each of these. Furthermore, since these 

 undoubtedly transmit characters that have been slowly ac- 

 quired by each parent form, the dissemination and wide prop- 

 agation by water ensures rapid spread of the species, and so 

 the opportunity for increased exposure of individuals of the 

 species to new environments, which might in time again start 

 new and rapidly acquired variations. Furthermore all known 

 facts lead us to conclude that the act of setting free of all such 

 entire or divided-up cell masses, and the existence of these 

 for a time free in the water, produces a greatly more rapid 

 gro^i:!! capacity than if such masses had remained inside the 

 parent walls. 



But, with the gradual evolution from motionless vegetative 

 cells (Zygnema, Cosmarium, etc.), or the evolution from swarm 

 spores, of complemental sex-cells, a highly important and 

 accelerating factor in evolution was established. For the 

 principle involved in Darwin's aphorism above quoted evi- 

 dently carries with it also a profound advantage to each result- 

 ing organism formed from a cross-fertilized egg. In no way 

 perhaps does this appear more strikingly than in diverse crosses 

 of some flowering species. 



Thus the writer has drawn attention to hybrids of the genus 

 Nepenthes (78: 446) that exhi})it combined characters of both 

 parents which make the hybrid more virile than either parent. 

 The same is true of some hybrid sarracenias, orchids, hippe- 



