PHYSIOLOGY. 



8*7 



production, and is therefore inclined to suppose 



tb*t the question is not \et solved. On meas- 

 uring the heat production of the same animal in 

 mlil and warm air, the author found it smallest 

 in air <>f medium temperature, becoming creator 

 in lower and in higher temperatures. In this 

 case regulation of the animal tcm|>eraturc < .in 

 be effected only by changes of the coefficient of 

 emission of heat from the skin caused by changes 

 of circulation. Hut for longer periods that reg- 

 ulation is insufficient. Animals produce more 

 heat in winter than in summer. If nourished 

 with the same food sufficient to maintain their 

 weight constant in winter they do not oxidize 

 the whole in summer, and therefore they gain 

 in weight. Ricldy nourished animals produce 

 less, sparely nourished animals more heat than the 

 calculation gives. Between the cases is a third 

 one in animals sufficiently nourished, or such as 

 take in as much nutriment as serves to maintain 

 their weight unchanged for a long time. In 

 their case only, the amount of heat produced is 

 really equal to that calculated upon the com- 

 bustion of the constituents of food. But in 

 these cases also variations are observed, caused by 

 changes of temperature, muscular motion, etc. 

 Thus, if a well-nourished animal is starved, the 

 heat production remains unchanged for three or 

 four days, the animal burning its stored-up materi- 

 als and losing much of its weight ; only then is it 

 suddenly reduced to a lower amount. If now food 

 is given again, heat production remains small, 

 the weight increases, and then three or four 

 days later the heat production increases and 

 reaches its former amount. If a sufficiently 

 nourished animal takes in all its food once a 

 day the heat production varies very regularly in 

 the twenty-four hours. Similar changes go on 

 in the expiration of carbonic acid. 



A committee of the British Association report 

 on the physiological action of the inhalation of 

 oxygen in asphyxia, that in the case of asphyxi- 

 ated rabbits oxygen is of no greater service 

 than air ; that pure oxygen when inhaled by a 

 healthy man for five minutes produces no effect 

 on the respiration or pulse ; that oxygen pro- 

 duces no effect upon a patient suffering from 

 cardiac dyspnoea, either on respiration or on the 

 pulse; that an animal can be kept for a long 

 time in a chamber containing 50 per cent, of 

 carbonic acid without a muscular collapse, pro- 

 vided a gentle stream of air or oxygen be allowed 

 to play upon the nostrils. 



Fishes in badly ventilated aquaria give vari- 

 ous signs of oppression, such as restlessness, 

 frequent gasping, mounting to the surface, leap- 

 ing into the air, etc. Experiments have been 

 made by Duncan and Hoppe-Seyler to ascertain 

 to what point the oxygen content of the air 

 may be lowered before fishes indicate uneasi- 

 ness. They were made with tench, trout, and 

 crawfish in an elliptical glass vessel, with pipes 

 for injecting and removing water and air, etc. 

 In one case a pipe communicating with a cham- 

 ber in which was a live rabbit conveyed to the 

 fishes air impoverished by the latter's'breathing, 

 while the behavior of rabbits and fishes in the 

 same air could be compared. With from 4 to 3 

 cubic centimetres of oxygen in the litre of 

 water the fishes seemed well and content, and 

 with the corresponding oxygen tension in the 



air (H to 11 volume percentage) the rabbit was in 

 no difficulty. With from !? to 0-b cubic centi- 

 metres of oxygen in the water the trout were, 

 evidently ill at ease, and if the condition con- 

 tinued they died. The tench and crawfish, how- 

 ever, stood" still further reductions, the former 

 finding relief at the surface. Reduction of the 

 oxygen to zero soon produced the worst results. 



Speaking in the Physiological Society of Ber- 

 lin on heat regulation in man, Prof. Zuntz said 

 that the store of heat in the human body is at 

 any one time very large equal, in fact, to nearly 

 all the heat produced by the body during twen- 

 ty hours; hence the heat given off to a calorim- 

 eter during a given period can not be taken as 

 a measure of the heat production. This deter- 

 mination must be based rather upon the amount 

 of oxygen consumed than of carbonic-acid gas 

 given off. Experiments were made to ascertain 

 what alteration the gaseous interchange of the 

 body undergoes by the application of cold. The 

 observations were made on a number of men 

 whose respiratory gases were compared during 

 rest, when they were at one time clothed, at 

 another time naked, at different temperatures, 

 and in warm and cold baths. Each experiment 

 lasted from a half hour to an hour. The results 

 exhibited great diversity, which was explained 

 by the author's own subjective heat sensations 

 when he was himself the person experimented 

 on. After the first impression due to the ap- 

 plication of cold was overcome, he found it easy 

 to maintain himself in a passive condition ; sub- 

 sequently it required an effort of the will to re- 

 frain from shivering and throwing the muscles 

 into activity, and finally even this became no 

 longer possible, and involuntary shivering and 

 muscular contraction supervened under fall of 

 bodily temperature. During the first stage of 

 cooling his oxygen consumption showed a uni- 

 form diminution ; during the period also in 

 which shivering was repressed by an effort of the 

 will cooling led to no increased consumption of 

 oxygen ; but as soon as shivering became invol- 

 untary there was at once an increased using up 

 of oxygen and excretion of carbonic acid. This 

 may be taken as showing that in man, and pre- 

 sumably in all large animals, heat regulation as 

 dependent upon alteration (fall) in temperature 

 of the surrounding medium does not exist. The 

 increased heat production is rather the outcome 

 of the movements resulting from the applica- 

 tion of cold to the body. In small animals 

 there undoubtedly exists a heat regulation de- 

 pendent upon an increased activity of chemical 

 changes in the tissues set up by the application 

 of cold to the surface of the lx>dy. 



Circulation. An investigation has been 

 made by M. Potain to obtain the interpretation 

 of the cardio-pulmonary sounds resulting from 

 the movements communicated to the lung by 

 the heart, and the local phenomena produced by 

 these movements. The general movement, as 

 indicated by the tracings, is during systole a 

 rapid retreat of the surface and an equally rapid 

 translation to the right; that is. in fact, the 

 well-known torsional motion. At the end of the 

 ventricle the retreat is only effected toward 

 the end of the systole. At the beginning of 

 diastole the whole wall rapidly collap-es; it 

 then rises, slowly at first, as the blood gradually 



