186 Causes and Course of Organic Evolution 



would in no way prohibit the possibihty of the former character 

 reappearing in the future — and it might be remotely removed 

 — descendants, were the environal stimuli such that the char- 

 acter or type of energy response was again called forth. But 

 by that time many other alterations or replacements might 

 have taken place, so that, when the resubstitution has been 

 effected, it no longer is reformed into the exact type of organism 

 that before showed it, combined with other characters. 



In other words, every plant and animal possesses a common 

 heritage of a stock lot of energy-combinations ^^'ith ether par- 

 ticles of varying complexity, that we term material characters. 

 These undergo definite permutations and combinations, ac- 

 cording to environal stimulations and relations that definitely 

 affect them. With the gradual evolution of the earth, since 

 organic hfe first appeared on it, many environal agents have 

 been successively called into play, which have added to the 

 series that we might call the inorganic agents and which include 

 varying intensities of light, heat, and other energies, chemical 

 and physical characters of the soil for plants, or of plant and 

 animal food for animals. 



But the organic agents that often cause keen "struggle for 

 existence" on the one hand or progressive evolution on the 

 other are too much overlooked biologically. The parasitic 

 fungi that infest plants and animals, the flowering parasites 

 like dodder (Cuscuta) and broomrape (Orobariche), the ani- 

 mals that prey on plants or other animals, all cause either 

 mechanical or irrito-chemical stimulation and analysis that 

 the infested organism must either counteract, overcome, or 

 die before. 



Again the varied intimate beneficial adaptations between 

 the flowers of higher plants and visiting insects would have 

 been su])erfluous during the devonian epoch, when, according 

 to all i)resent knowledge, neither the groups of insects nor of 

 plants that are adapted to each other had evolved. But evi- 

 dently during the permian age both were slowly being evolved, 

 and by environal action and reaction through millions of 

 succeeding years the stimulating action of insects so molded 



