552 THE POPULAR SCIENCE MONTHLY 



facts of more importance than biological in their interpretations of 

 society; and why it is reasonable, for the present at least, to hold the 

 eugenist's fear of decadence a trifle overdrawn. 



Surplus energy, as used in this paper, means the amount of energy 

 available for life-processes which is possessed or obtainable, by any 

 organism, over and above the amount which is necessary for survival at 

 any given time. 



Surplus energy, in this sense, assumes many forms. Bodily vigor 

 and long life are not the only manifestations of it. Such material goods, 

 also, as are immediately available for restoration of depleted bodily 

 vigor come under the general heading. Moreover, any structural or 

 other changes in an organism which improve its chances of survival, 

 increase the surplus. The development of useful instincts and the dis- 

 covery of useful methods of controlling nature and producing wealth — 

 these, too, increase the surplus. Bettered social organization plays its 

 part as well. In fact, in close analysis, every trait and every act of any 

 unit of a group in some way affects the surplus. It is evident, therefore, 

 that only the more important phases of the subject can be considered 

 here. The term social surplus follows directly from the meaning of 

 surplus energy. The social surplus is merely the sum total of surplus 

 energy existing in the individuals composing a social group or imme- 

 diately available to such individuals. 



What were the first -steps in the development of surplus energy in 

 the long series of organic changes that led to the evolution of the higher 

 animals and man, none can say. If it is permissible to hold, however, 

 that the earliest ancestors of man were similar in character to the lowest 

 forms of animal life now existing on this planet, we may at least sur- 

 mise the general character of those early advances. 



Consider, for a moment, the great advantage over the lowest pro- 

 tozoa, certain structural differences give that large group of single- 

 celled animals called Ciliata. The microscopic Amoeba proteus, which 

 may be taken as representative of the very lowest animals, is structurally 

 most simple. Its form is irregular and is continually changing in 

 response to stimulation. Although the internal substance of its body 

 shows some differentiation, there is nothing remotely resembling special- 

 ized sense organs. According to Jennings, one of the foremost author- 

 ities on the behavior of the lower organisms, the amoeba has three char- 

 acteristic reactions to stimulation. These are, the negative, the positive 

 and the food-taking reactions. The first is a contraction of the part 

 of the animal stimulated when, for example, it comes into strong con- 

 tact with a solid obstacle. The negative reaction may cause movement 

 in a direction opposite to the point of stimulation. A positive reaction 

 to solid bodies occurs when a pseudopodium is pushed forward in the 

 direction of the stimulus and the animal moves toward the solid. The 



