68 4 THE POPULAR SCIENCE MONTHLY. 



In another stage of the inquiry we will learn the exaot effect which 

 restitutive material, when not accurately complemental, does actually 

 exert on the protoplasm. I will here only mention that it has, very 

 demonstrably, only the power specifically to deteriorate the same, and 

 not in the least the power to give it any impulse toward higher develop- 

 ment. In the course of organic progress it is the living substance which 

 lifts the food to the level of its own requirements ; not the food which 

 confers higher vital powers on the protoplasm. 



There remains only one path, then, through which development can 

 make its entry into the living substance, and this is be it fully under- 

 stood the infinitely toilsome elaboration of molecular complexity by 

 means of ever-reiterated functional disintegration. If it, namely, should 

 happen, that the dynamical influences of the medium are so attuned as 

 to shift and complicate by force of their sundry specific modes of 

 operation the molecular equilibrium of the protoplasm, ever so im- 

 measurably little at a time, then, by incessant perseverance, an appre- 

 ciable organic effect may, at last, be attained. 



There are strong reasons which make it highly probable I do not 

 say certain, because it lies in the nature of the process that it cannot 

 be directly witnessed but there are manifold occurrences which make 

 it very evident that this mode of development is actually the one 

 adopted in Nature. 



In a general way we all know, with perfect certainty, that previous 

 functional exercise of an organ fits the same all the better for further 

 functional performances. Use develops functional structure ; disuse 

 involves its atrophy. All educational acquirement rests on this foun- 

 dation, and also all degradation of skill or culture. 



We will endeavor to form some mental representation of the activi- 

 ties which are elaborating these great and evident results. 



The energy of the dynamical influences is exerted on protoplasm in 

 the course of chemical composition. It is a substance in process of 

 molecular cumulation which encounters, in its onward flow, the forces 

 of the medium. The foremost part of an advancing conical projection, 

 for instance, will consist of higher material than its lateral part, and 

 will therefore be differently affected even by the same forces of the me- 

 dium. But, if we further take into consideration that the influences of 

 the medium are themselves of a manifold nature, each kind affecting 

 the protoplasm with a specific energy of its own, it can be readily con- 

 ceived that .a most complicated molecular disturbance must ensue. 

 This must be all the more the case in a substance in which the forces 

 of the medium have not each their definite, circumscribed, and attuned 

 channel of functional stimulation ; but are attacking more or less every 

 part of its circumference. 



Dynamical considerations, too abstruse to be here introduced, make 

 it extremely probable that a preponderance of effect in favor of the 

 dynamical energies best attuned to the highest, foremost portion of 



