522 



SCIENCE 



[N. S. Vol. XXIX. No. 744 



in a rapid, orderly and economical manner. 

 Chittenden has taught us to beware of an 

 excessive quantity of protein food, even 

 though it may be questioned whether 

 it is most economical to reduce our 

 daily protein intake to as low a point 

 as forty or fifty grams. Digestion should 

 not be ' delayed. Oxygen starvation 

 is most deleterious; and the two re- 

 quisites for a sufficient intake of this es- 

 sential element are, first, a sufficient supply 

 outside the body and, secondly, an efficient 

 respiratory mechanism. It can hardly be 

 questioned that a rapid anabolism and a 

 rapid katabolism are advantageous. The 

 storage of much nutriment in the cells, in 

 the form of glycogen or fat, is like putting 

 one's money in a safe-deposit compartment, 

 where it lies with no interest return to its 

 owner. Food should be quickly utilized, 

 either to form protoplasm or to yield en- 

 ergy. There is also reason to believe that 

 intermediate katabolic products are harm- 

 ful to the tissues, and that they should be 

 quickly turned into the final excretory 

 products and cast out. Thanks to the 

 labors of Starling and others, we are now 

 beginning to realize how far-reaching is the 

 control of the various tissues by distinct 

 chemical bodies, or hormones, produced in 

 other tissues. Any interference with the 

 production of hormones is obviously an ob- 

 stacle to efficient action. 



A second criterion of efficiency is that 

 the body's physical, as distinct from its 

 chemical, processes shall be adequate to the 

 body's needs. Voluntary and involuntary 

 muscles should possess size, toughness and 

 contractile power sufficient for both ordi- 

 nary and extraordinary demands. The 

 heart should be able to resist a high blood 

 pressure without detriment to its muscle 

 fibers or valves. The capillary bed should 

 be capacious. Vasomotor response should 

 be ready. Respiratory organs should be 



capable of quickly bringing in oxygen and 

 quickly eliminating carbon dioxide. Os- 

 motic exchange should be rapid. Secreting 

 and excreting organs should be richly sup- 

 plied with blood and lymph, and capable 

 of quickly supplying their products. The 

 amount of energy utilized in mechanical 

 work should be as high as possible in pro- 

 portion to the total amount of energy ex- 

 pended, and the work of Zuntz and others 

 has shown that the former can be largely 

 increased by training. 



A third criterion of efficiency is accuracy 

 and delicacy in the activity of the organs 

 of special sense. 



And a fourth criterion of efficiency is a 

 skilful working central nervous system, 

 playing its part effectively, whether with 

 or without psychic accompaniments, and by 

 means of excitation and inhibition exerting 

 an adequate coordination and control of all 

 the bodily processes. 



From this summary of some of the fac- 

 tors that make up physiological efficiency 

 I turn to one of the most important ob- 

 stacles to its development. This is fatigue. 

 Fatigue is a general biological phenomenon 

 — wherever protoplasm exists, there fatigue 

 is possible. Given everything else, it is 

 fatigue that loses races and it is absence of 

 fatigue that wins games. Fatigue occurs 

 in both physical and psychical processes. 

 It is normal, and yet it may easily overstep 

 its ill-defined normal boundaries and be- 

 come markedly pathological. While orig- 

 inating, it may be, in one tissue, it radiates 

 to aU others and touches the most remote. 

 It manifests itself in striking physical phe- 

 nomena, yet it is primarily a chemical one 

 — a phenomenon of metabolism. It seems 

 strange that, with all the centuries during 

 which mankind has struggled against it, 

 fatigue should stiU remain largely an un- 

 solved problem. We seem to be on the 



