1902.] NATURAL SCIENCES OF PHILADELPHIA. 191 



kind, aud mode of interaction of those activities of parts known 

 as functions. Here would presumably be found a progress from 

 the more generalized to the more specialized, accompanying the 

 evolution of the organism, just as in structural relations. (2) 

 Physical or Dynamical, one based upon the so-called physical ener- 

 gies or motions ; for such motions might be found to show successive 

 complexity, according to changes within the organism. (3) 

 Chemical, for increasing complexity and instability of the sub- 

 stances composing the organism might go on parallel with the course 

 of racial development. (4) Ecological, based upon the relations 

 of the organism to its environment, its kinds of habits and their 

 modifications, its geographical distribution, its general responses to 

 environmental stimuli. (5) Psychical, dealing with its mental 

 operations (this might be classed with the physiological). 



Now these possible kinds of classification fall into two gi-oups, 

 the physical and chemical, and the morphological, physiological, 

 ecological and psychical ; for while the physical phenomena of an 

 organism may be considered by themselves, and the chemical 

 equally so, all the other kinds of phenomena are closely correlated. 

 We might term the physical and chemical aspects inorganic, and 

 the others organic, were these expressions not now becoming some- 

 what obsolete. There may have been an evolution of the " inor- 

 ganic " as well as of the " organic " energies of organism, so that 

 d priori a phyletic classification might be based upon the physical or 

 the chemical phenomena. But how much has been determined of 

 the evolution of physical and chemical energies ? Certain of their 

 present actions are becoming explained, by gradual synthesis many 

 com|X)und substances have become built up, and in change in the 

 substances possibly the physical movements of these substances 

 become changed; but are there facts to show that all substances 

 have been derived from one primeval substance, or that all kinds of 

 physical motion are referable to one ancestral kind ? The uncer- 

 tainty on these points, the lack of relatively positive facts, the great 

 hiatus in our knowledge of physical and chemical relations as studied 

 particularly in organisms, are sufficient reasons for neglecting at 

 the present time any attempt to base a phyletic classification of or- 

 ganisms upon such relations. Until all the phenomena of growth 

 and structure in organisms can be expressed in purely physical and 

 chemical terms, which so far has not been possible, it would be in- 



