464 PROCEEDINGS OF THE ACADEMY OF . [1892. 



Prof. Morse's position that the culture experiments of Dr. 

 Dallinger in training monads to withstand gradually increased tem- 

 perature, until endurance of 158°F. was reached, was an illustration 

 of natural ><electto)i pure and simple, is also an illustration of the 

 oversight by Neo-Darwinians of the essential energy-factor of the 

 problem. 



Since the monad cultures were kept continuously at a gradually 

 rising temperature, there must have been continuous and successive 

 responses in the mechanisms of the protoplasm of the successive 

 o-enerations to the new conditions, else adaptations could not be 

 effected. The failure to apprehend the fact of the continuity of 

 adaptive processes, while the whole burden is thrown upon the dis- 

 continuous selective process, is most extraordinary. If none of the 

 monads involved in the earlier stages of the experiment, hadunder- 

 o-one certain internal changes owing to the persistence of the new 

 energy-conditions of heat, none would have been modified so as to 

 be selected as the progenitors of a series of generations, capable of 

 sustaining even greater extremes of temperature. 



The adaptive process in living forms where energy always is con- 

 tinuously involved, may be fittingly compared to the idea of con- 

 tinuous number, as understood in the calculus, in contrast to 

 discontinuous or integral number in ordinary arithmetic, and 

 tvpical of the discontinuous process of the selection of integers, or 

 individuals of a race by means of natural selection. This energy- 

 factor cannot be so conveniently ignored, as it is every time the 

 Neo-Darwinians assert that the development of new characters is 

 entirely due to natural selection. 



In the paper by the writer, published in 1890, the idea was 

 advanced that heredity itself must be ultimately interpreted in con- 

 sonance with the doctrine of the conservation of energy. It was 

 then stated that a theory of heredity something like the following 

 would have to be assumed : — 



" In the first place, the supposition of a germ-plasma distinct from 

 the plasma of the parent-body is a needless interjection into the 

 machinery of hypothesis of biological evolution. It does not 

 make the matter one whit clearer to suppose that the germ-plasma 

 is necessary, than to suppose that all of the living p)lasma of any and 

 every distinct species is an idioplasm, or is specific in so far as that 

 species is concerned. If we now suppose, as a consequence of the 

 action of the principle of physiological division of labor, first pro- 



