MACFARLANE: SYNCHRONISM IN PLANT STRUCTURES 325 



peeling of bark on twigs of trees and shrubs at exact time; or that 

 effect passage of food material from elaborating to storing centers, and 

 from the latter in turn to young developing organs. 



Even such irregular and delayed occurrences as already noted re- 

 garding the flowering during the present season of the Carolina poplar, 

 or during 1913 of the silver maple (A. saccharinum) represent fitful 

 and prolonged results due to weakened or cancelled tubes of energy- 

 stimulation expended over an extended period, as compared with the 

 normal succession of events that may be consummated within a few 

 hours on a definite day or days. So we might summarize as follows 

 our conclusions drawn from study of phenological and related events : 



1. For any one locality, under like environal surroundings, the 

 average annual period of seed-germination, leaf-formation or unfolding; 

 first period of blooming, dissemination of pollen, and other responses 

 by flowering plants, seem to be synchronous often to a day, and even 

 to certain hours of one day. 



2. In monoecious and dioecious flowering plants, under like en- 

 vironment, all evidence tends to indicate that maturation of compli- 

 mental floral organs is effected in exactly synchronous relation, and 

 so abundant pollination usually ensues. 



3. A like principle apparently applies to the maturation and 

 dispersal of spores and organs of conjugation. 



4. The behavior of plant hybrids strongly suggests that each is a 

 blended combination of parental characters as to period of leafing and 

 defoliation, of blooming and pollination, capacity for climatic resist- 

 ance and other phenomena. So each shows synchronous behavior in 

 its organs, that is a mean — all environal factors being considered — 

 between those of the parents. 



5. The principle, advocated by the writer for the past six years, 

 of environal action and organismal reaction, seems to hold true in the 

 organic as in the inorganic world, and only needs to be amplified and 

 demonstrated by increasingly accurate and extended observations on 

 plants over wide areas. 



• 6. In the evolution of all plants and of all plant parts, the funda- 

 mental and important consideration is the exact distribution of lines 

 or "tubes of energy" (Faraday) along otherwise inert material path- 

 ways; the lines of inflowing energy constituting stimulation actions, 

 the lines of outflowing energy constituting reactions on the part of the 

 organism. 



7. Such actions and reactions show an optimum, as well as a maxi- 

 mum and minimum of interrelation. The optimum for the indi- 

 viduals of each species, and for the organs of this, under like environ- 

 ment, often constitutes a phase-relation that recalls like phase-rela- 

 tions amongst inorganic bodies. 



