1892.] NATURAL SCIENCES OF PHILADELPHIA. 463 



This show of logical acumen by my Anglican critic, is useless ; 

 the facts are so overwhelmingly against him, as respects the evidence 

 for a mechanical theory of the evolution of the teeth, that there is no 

 other way in which they can be coordinated. This evidence is 

 cumulative in amount and character, and is also an illustration of 

 the cumulative effect of the secular display of a portion of the 

 energy dissipated by a series of organisms, straining even their 

 hard parts into new configurations which have became hereditary, 

 because the soft parts underlying them have been correspondingly 

 modified and moulded by physiologically developed stresses, which 

 have become, so to speak, permanently expressed as physiological 

 strains.^ As yet there is no proof of the slightest scientific value, 

 that dynamically acquired and thus cumulatively developed charac- 

 ters cannot be inherited, despite all the evidence, mostly worthless, 

 accumulated by Weismann, Poulton and others. For the unfair 

 manner in which the term " acquired character " is used in all sorts of 

 senses, restrictions and limitations by Weismann himself, see a 

 criticism* by C. C. Nutting. 



In point of fact, every time a new character appears it is self- 

 evident that energy must be expended in order that the necessary 

 movement of parts may be effected ; in order that a new form of 

 the organism, or of some part of it, may be assumed. So far from 

 its being a fact that dynamicallij acquired characters cannot be inher- 

 ited, it is an irrefragable fact that dynamically developed characters 

 are the only ones that can he inherited. How this is accomplished 

 is a matter for further research. 



If refuge is sought in a germ-plasm in which capacities for varia- 

 tion are assumed to inhere, it must be assumed that it operates 

 according to a law peculiar to itself, and in defiance of all known 

 external and physical influences, such as modify or control the 

 movements of the constituent particles and masses of all other 

 bodies. Heredity seems to inhere a la Weismann in the germ 

 plasm, something after the manner of the inherence of " horologity," 

 or time-keeping properties in a clock, as long ago suggested by Prof. 

 Huxley, when he was exposing the untenable position of the advo- 

 cates of " vitality," as a kind of energy with no affiliations to other 

 kinds. 



^ The words " stress " and " strain " are here used by me in the same sense as 

 by engineers and physicists. 



♦American Naturalist, XXVI, 1892, p. 1009. 



