328 POPULAR SCIENCE MONTHLY. 



involves the least expenditure of energy. In tlie case of inor- 

 ganic movements there is no such economy, since those move- 

 ments are mere effects, and comply unvaryingly with the laws of 

 mechanics. Finally, the exertion of choice by an organism does 

 not determine whether movement shall take place in the direc- 

 tion of the least resistance or not for that is the inevitable mode 

 of all movements, organic as well as inorganic but whether the 

 energy expended in the differential or greatest stress producing 

 movement shall be a larger or a smaller quantity. 



We have next to note that the economy of energy which is 

 possible in organic movements has two forms. There is economy 

 in the realm of the conscious will, exemplified in movements by 

 which animals reach various ends ; and there is an economy in 

 the realm of the unconscious life of the organism by which the 

 parts thereof rearrange themselves in such a way as to lessen the 

 expenditure of effort in the work of maintenance. For, whenever 

 function is imposed by the organism upon certain of its parts, such 

 parts, moving into configurations of least resistance, set up the 

 intelligent adaptations which we know as organs. The only dif- 

 ference between a tool and an organ is that the former has been 

 consciously shaped by man, whereas the latter has arisen through 

 the unconsciously effected rearrangements of living molecules 

 upon which function has been imposed by the organism. All 

 organs, like all tools, are paths of least resistance, ways of reach- 

 ing ends of organic maintenance with a minimum expenditure of 

 effort. Simultaneously, moreover, with the saving of energy 

 spared through the gradual perfecting of organs, there goes on a 

 gradual improvement of the ends which such organs are uncon- 

 sciously produced to reach. For this is simply to say that all 

 effort saved by an organism through increase of the efficiency of 

 its organs and processes goes the circumstances being favorable 

 to increase the complexity and delicacy of its relation to the 

 environment, as well as to enlarge the scope of the activities of 

 maintenance. 



The way in which organic molecules move into configurations 

 that offer the least resistance to their special activities may be 

 seen in similar structural formations which are more or less 

 unconsciously assumed by human beings. One of these is the 

 habit of taking turn by people waiting, say, at the box office of a 

 theatre a configuration which is assumed more or less uncon- 

 sciously, because it is the one which, under the whole of the cir- 

 cumstances, involves conditions of least resistance. There is a 

 similar selection of conformations involving a maximum of ease 

 in the manner in which pedestrians avoid collision with each 

 other. The throng in movement on the crowded sideways of a 

 great city divides itself naturally and without conscious delibera- 



