ASPECTS OF KINETIC EVOLUTION 20O. 



the scientific world because they have been thought to combine 

 the characters of animals and of plants and thus to afford a con- 

 necting link between the two organic kingdoms. Beginning with 

 such a primitive and undifferentiated form of life, it is easy to think 

 of the animals as gradually specializing the power of locomo- 

 tion, the plants the alternative powers of morphological and 

 physiological adjustment. The animals excel in seeking their 

 own environments, the plants in the ability to take what comes. 



The purpose of this rehearsal of elementary facts is merely 

 to convey, if possible, the suggestion of an idea of organic 

 elasticity, so to speak, of which muscular contractility and loco- 

 motion are the extreme specializations, but which extends into 

 all departments of organic activity, morphological as well as 

 physiological. Some may still prefer to say that the environ- 

 ment " causes" the adjustments to be made, but it will remain 

 none the less true that the organisms themselves make the 

 adjustments. 



Zoologists speculate on such questions as whether the eggs of 

 Vancouver wood-peckers, if transferred to Arizona, would hatch 

 Arizona wood-peckers, or whether the transferred individuals 

 would gain Arizona characters in a few generations. What the 

 wood-peckers might or might not do depends on the amount of 

 organic elasticity which they may happen to possess, but the ex- 

 periment is unnecessary for answering the general question, 

 since plants show a high development of these powers of prompt 

 adjustment to diverse conditions. It is not even necessary that the 

 eggs be hatched in Arizona. Many plants, as already noted, 

 can adjust themselves to such changes at any stage of their ex- 

 istence, and are regularly accustomed to do so. They are both 

 fish and flesh. In water they have the form, structure and func- 

 tions of other strictly aquatic species ; on land they are equally 

 ready to behave as terrestrial species. 



Needless to say, hundreds of plants have been described as 

 new species which proved afterward to be only land, water, 

 shade, sun, or other environmental forms of previously known 

 species, and such unnecessary "species" continue to be de- 

 scribed. There is no way to ascertain from a few her- 

 barium specimens whether their differences represent the results 



