466 EXPEEIMENT STATION EECORD. 



investigations reported were carried out witli a special form of respiration 

 apparatus (E. S. R., 21, p. 665), and witli a bicycle ergometer described in a 

 previous publication of tlie IT. S. Department of Agriculture (E. S. R., 21, p. 

 68), and a second instrument vphich was a replica of it. Two essentially funda- 

 mental questions were considered, namely, the character of the material burned 

 in the body before, during, and after muscular work, and the relationship be- 

 tween the amount of productive effective muscular work and the total heat 

 output. 



The subjects of the experiments were all young men in perfect health. Four 

 of them were accustomed to bicycle riding, while the fifth, with whom most of 

 the experiments were made, was a well trained professional bicyclist. The ex- 

 periments were all carried out in the postabsorptive state, that is, at least 

 twelve hours after the last food had been taken. The investigation as a whole 

 covered several months and involved several hundred experiments. 



The results showed that during severe muscular work there is a distinct 

 alteration in the character of the materials burned in the body. The evidence 

 indicated a selective combustion of carbohydrate material, though the experi- 

 ments do not point to an exclusive combustion of carbohydrate during muscular 

 work. 



The greater part of the experiments was devoted to a study of the relation- 

 ship between the total heat output and the effective external muscular work, 

 thereby giving information in regard to the mechanical efficiency of man. The 

 report also takes into account other important questions relative to the muscular 

 work of man, such as the effect of muscular work on the pulse rate, the body 

 temperature, the mechanics of respiration, and the drafts upon the body ma- 

 terial, the maximum working capacity of man, and particularly the after-effects 

 of work. A certain amount of evidence was provided by the experiments for a 

 comparison of results obtained with trained and vmtrained individuals. 



Under certain conditions, it is pointed out, particularly when the subject is 

 riding with a moderately severe load and immediately begins riding with a 

 very severe load, it is possible to superimpose a load upon the human body so 

 that 40 per cent of the increment in the total heat output may be in the form of 

 effective external muscular work transmitted to the machine, such as the bicycle 

 ergometer. The experiments gave no indication of the possibility of " over- 

 loading" the human machine so far as mechanical efficiency was concerned. 

 Obviouslj' the power of human endurance is limited, but an interesting point 

 brought out is the fact that the professional bicyclist performed all of the ex- 

 periments without food and that on at least one day he did an amount of work 

 equal to a " century " run over ordinary roads. This experiment gave the data 

 for computations with respect to the probable amount of available glycogen in 

 the human body. 



An extensive review of the earlier literature with an analysis of the results 

 obtainetl by former investigators accompanies the report. 



The temperature of expired air and air in the lungs, A. Loewt and H. 

 Geriiartz {Pfliigcr's Arch. Physiol. , 155 (1913), No. 3-5, pp. 231-2U, figs. 3).— 

 An extended series of observations is reported and discussed. 



ANIMAL PRODTJCTION. 



Introduction to heredity, R. B. Goldschmidt {Einfiihrung in die Vererlmngs- 

 wissoisclntft. Lcipsic and Berlin. 1913, 2. ed. rev. and enl., pp. XII-\-5It6, figs. 

 189). — This volume treats of the theories of inheritance, variation, mutation, 

 hybrids, and other related subjects. 



