A BIOLOGICAL FORECAST 3° 5 



should be rightly labeled, but to stigmatize them as necessarily inferior 

 to the natural products is, to say the least, unprogressive. We do not 

 object to artificial indigo because the chemist has superseded the green 

 plant in its manufacture. Why, then, should we object to a currant 

 jelly composed of wholesome artificial products? It may not only be 

 as good as the old-fashioned kind, but I can imagine that a connoisseur 

 in this new venture might impart to it a flavor even more delicate than 

 that from the kitchen. Our descendants, I am sure, will some day sit 

 down to dinners of synthetic dishes, the products of clean laboratories, 

 with as much appetite and pleasure as we now partake of a meal hewn 

 from the animal and dug from the earth, and we must not object if 

 they prefer, on esthetic grounds, the source of their food to that of ours. 



But food is only one of the many things we need. We number our- 

 selves among the very few organisms that use tools and we need energy 

 to drive many of our tools. Historically we have abandoned in much of 

 our work the muscle for the steam engine. Contrast the construction of 

 a modern building by a handful of Italian workmen and a donkey 

 engine with the wall pictures we have of the long lines of Egyptian 

 slaves straining every muscle as they pull a heavy load at the end of 

 a rope. 



But have we done best to ignore the muscle? When this organ is 

 functioning at its highest, it yields two kinds of energy, heat and power 

 to do mechanical work about in the proportion of two thirds heat to> 

 one third work. From the energy that enters the ordinary steam engine 

 about one tenth is given back in work and the other nine tenths are- 

 dissipated as heat. Even in the highest grade of turbine engines, this 

 efficiency seldom reaches as much as a quarter of the available energy. 

 Thus the muscle returns us over thirty per cent, of its energy in 

 effective work, and the best steam engines only about twenty-five per 

 cent. If we knew the secret of muscle action, I have no doubt that 

 a mechanism could be constructed that would far outrun the steam 

 engine as a means of doing work. 



Another kind of energy that we seek is light. Primitive man was 

 forced to content himself with the sun by day and the moon and stars 

 by night. When he first struck fire, artificial light came as well as 

 warmth, and from that day to this we have witnessed a long succession 

 of improvements in the production of artificial light. But in none of 

 these has man rid himself of the association of heat with light. Every 

 device for illumination that has been put forward } r ields more heat 

 than light. Our ordinary gas flame yields between one and two per 

 cent, of light and the remaining ninety-eight or -nine per cent, is lost 

 in heat. No wonder that the modern gas corporation is advertising 

 itself as a convenient source of heat and power. Many of us who serve 

 it as consumers have come to regard this by-product as the most impor- 



vol. Lxxxur.— 21. 



