PHYSIOLOGY. 



577 



those to which workers in deep bridge caissons are 

 exposed, found that under rapid increase of pres- 

 sure amounting to two atmospheres and rapid 

 diminution to ordinary pressure no effects oc- 

 curred beyond slight increase of the respiratory 

 oscillations and slightly diminished frequency of 

 the pulse. He therefore regards the mechanical 

 congestion theory of caisson disease as untenable. 

 But how, the Lancet asks, does he explain the 

 hemorrhages from nose and ears that have been 

 observed when the pressure is too suddenly re- 

 leased ? 



Experiments on the temperature of the animal 

 body during fasting and the rate of assimilation 

 of carbohydrates conducted at the University of 

 Genoa and described by Prof. Ugolino Mosso are 

 particularly interesting in that they establish the 

 efficacy of sugar in raising the temperature of an 

 animal when it has fallen during a period of fast- 

 ing. From one to four grammes of sugar per kilo- 

 gramme were found to cause a rapid rise of tem- 

 perature in the first ten or fifteen minutes; in 

 from one to two hours the temperature reached 

 a maximum, and remained constant or elevated 

 for an interval of time varying with the amount 

 of sugar introduced. The effect of sugar is most 

 marked after a long fast, when the temperature 

 is lowest. The action of bread is in some respects 

 opposite in character. The temperature rises more 

 slowly after the introduction of bread than after 

 sugar, and the rise in this case is most rapid for 

 animals whose period of starvation has been short, 

 and whose temperature is not too low. 



Circulation. In continuation of his researches 

 on the physiology of the mammalian heart, J. A. 

 Me William has studied the influence of chloroform 

 on the rate of heart beat, with observations on the 

 effects of asphyxia. The general effect of chloro- 

 form upon the pulse of the cat appeared to be the 

 same as in man first, a stage of acceleration, and 

 then one of moderate or slow rate. It was found 

 that: 1. During relatively light anaesthesia there 

 might be (a) a brief phase of slowing, followed 

 usually by acceleration, or (ft) acceleration without 

 primary slowing; and convulsive movements were 

 marked. 2. With deeper anaesthesia acceleration 

 was the rule, associated with respiratory effort 

 and diffuse motor excitation. 3. In still deeper 

 anaesthesia there might be no change in pulse rate 

 for a time, and the slowing convulsive movement 

 was absent or slight and late in development. 

 The acceleration was essentially due to dimin- 

 ished activity of the vagus center, and was marked 

 only when contraction of skeletal muscles was ex- 

 cited. Slowing depended mainly on increased ac- 

 tivity of the same center, but in the final phase 

 there was direct influence on the heart itself. 



The results of systematic observations on the 

 conditions of students participating in athletic 

 games have been published by Prof. Alfred Stengel, 

 M. D.. of the University of Pennsylvania, and an 

 account of similar studies with students of the 

 University of Cambridge is given by Prof. Clifford 

 Allbutt in the fifth volume of his System of Medi- 

 cine. Important agreements and a few differences 

 appear in the conclusions reached by these authors. 

 By percussion and auscultation Prof. Stengel was 

 able with a brush dipped in oil to map out on the 

 surface of the chest the borders of the heart, the 

 mid-sternal line, the episternal notch, and the out- 

 linos of the upper ribs. The lines thus obtained 

 were transferred to tracing paper applied to the 

 c-host, and were thence reproduced on drawing 

 paper. In watching the effects of training at- 

 tention was first drawn to the ease and fre- 

 quency with which a soft systolic murmur was 

 found to develop over the heart. In a special 

 VOL. XL. 37 A 



trial of 9 football players in the summer, the 

 prompt development of a very evident cardiac 

 murmur after a little exertion was noticed. But 

 during the succeeding autumn term the same men, 

 tested under similar conditions, gave no evidence 

 of cardiac murmurs. In one young man an ex- 

 tension of the cardiac limits was observed after a 

 half-mile race. The left border of the heart was 

 displaced to a point somewhat beyond the nipple 

 line, and the right border to a distance of about 

 two thirds of an inch beyond the corresponding 

 edge of the sternum. After the race a diffused 

 thrill was felt over the apex of the heart and in 

 the epigastrium, which was confirmed by ausculta- 

 tion, and the second pulmonary sound was dis- 

 tinctly heard. In the case of a half-mile runner, 

 twenty-two years of age, in whom the heart sounds 

 before the race were normal, a distinct systolic 

 thrill at the apex of the heart was perceived at 

 the conclusion of the race. A trained walker, 

 twenty-three years of age, in regular " form " for 

 three years, snowed an increase of the first sound 

 of the heart, together with a puffing systolic mur- 

 mur after the race. The right border of the heart 

 underwent no displacement in this case, but the 

 left border was displaced to the nipple line after 

 exercise. The author is of the opinion that a pre- 

 liminary overdistention of the right side of the 

 heart occurs after exercise, and is attended with 

 a certain amount of discomfort or distress; but 

 this eventually subsides when the athlete is said 

 to have recovered his " second wind." This con- 

 clusion, reached independently by him, is sub- 

 stantially the same as that arrived at by Dr. All- 

 butt. Dr. Stengel finds, further, that the pul- 

 monary arterial murmurs (heard in the second in- 

 tercostal space) are due to a dilatation of the 

 artery prior to its bifurcation, and are almost ha- 

 bitually present in young boys after exertion. A 

 distinct pulsation is likewise often felt in this situ- 

 ation. The cardiac systolic murmurs are, as a rule, 

 due to mitral regurgitation, but others are possibly 

 of cardio-pulmonary origin. Certain remote after- 

 effects are also mentioned as appearing in middle- 

 aged persons who have indulged freely in athletics 

 during youth. The author concludes that over- 

 distention of the heart is frequent as a result of 

 athletic contests, and may cause harm if the per- 

 son is in ill health or badly trained, and that 

 permanent hypertrophy with symptoms of palpi- 

 tation or distress are results not seldom met with. 

 Having determined the percentage oxygen ca- 

 pacity (between 16 and 21 in healthy men) and 

 the total oxygen capacity, J. S. Haldane and J. 

 Lorraine Smith computed the total volume of the 

 blood by calculation from the total and the per- 

 centage oxygen capacities, and the total mass by 

 multiplying the volume by the specific gravity 

 (about 1.055). The results of a number of ex- 

 periments on healthy persons showed that the 

 commonly accepted estimate of the mass of blood 

 as one twelfth of the weight of the body is much 

 too high, the average found being only about -^ of 

 the weight without clothes. As a general rule, the 

 mass of the blood (in proportion to body weight) 

 was found to be greater as the percentage oxygen 

 capacity was less, so that the total oxygen ca- 

 pacity (or the total amount of hemoglobin) is 

 relatively constant. Applying their method to 

 special affections, the authors found that in chloro- 

 sis the total oxygen capacity was maintained at 

 approximately the normal amount, while the per- 

 centage oxygen capacity diminished (for example, 

 below 50 per cent.), and the volume of the blood 

 was increased to a marked degree. The decrease in 

 the number of red corpuscles and the amount of 

 haemoglobin could not be regarded as due simply to 



