PHYSIOLOGY. 



soldiers on the slopes of Monte Rosa and upon him- 

 self in Turin. I'rof. I'golino Mosso finds tliat the 

 quantity of that substance expired by a man at an 

 altitude of 4.000 metres differs but little from that 

 expired at 'J?li metres above the sea level. The 

 author subjected himself to pressures as low as 34 

 centimetres of mercury without feeling any ill ef- 

 3 n present being still sufficient for 

 pur| iration : but when the pressure was 



reduced to 30 centimetres he began to find his 

 faculties impaired, and in one case felt a great want 

 of breath. After eleven or twelve minutes, he be- 

 came incapable of making accurate observations, 

 and the experiments had to be discontinued. 



The study of the hibernation of the marmot, by 

 M. R. Dubois. has shown tiiat besides being marked 

 uniformly by a diminution of the chemical ex- 

 changes, as has been observed by all authors, the 

 exehanu'es consist in accumulation of carbonic acid 

 in the blood and a smaller expiration of that gas. 

 The respiratory quotient, or the relation between 

 the oxygen absorbed and the carbonic acid pro- 

 duced, goes on diminishing and approaches - 5, 

 while in the animal awake the relation is near 

 unity. The inference that the fats especially are 

 consumed in hibernal torpor is confirmed by micro- 

 scopic examination of the animals made after a 

 long period of sleep. M. Dubois has confirmed, 

 further, the fact already vaguely mentioned, that 

 it is not necessary to cool the ambient medium to 

 the freezing point to put a marmot to sleep. In- 

 deed, if a sleeping marmot is placed in a tempera- 

 ture below the freezing point it will awake. The 

 reason of this seeming anomaly affords another illus- 

 tration of the theory of the natural defenses of the 

 organism. If the animal continued motionless and 

 torpid at a temperature below the freezing point it 

 would not be able to defend itself against the cold, 

 and would perish. The awakening is brought about 

 partly by the irritation caused by an accumulation 

 of urine and partly by the action of the ganglions 

 of the great abdominal sympathetic. 



In relation to mountain sickness. Prof. Zuntz has 

 given an account of experiments on respiration car- 

 ried on by him in conjunction with Dr. Schumburg 

 at great altitudes on Monte Rosa. He found that 

 when resting the consumption of oxygen was greater 

 than at lower levels, but not in a very marked de- 

 gree, and differed with different individuals. Dur- 

 ing work, which consisted in climbing a steep in- 

 cline, the amount of oxygen consumed was. per 

 kilogrammetre of work, nearly three times as great. 

 indicating a correspondingly increased expenditure 

 of energy. In accordance with these facts, what is 

 called mountain sickness can not be due chiefly, if 

 at all, to the diminished partial pressure of oxygen 

 at the higher level. The author considered that it 

 was rather the outcome of a lessened cardiac activity. 

 brought about by the powerful stimuli of insolation 

 acting on the eyes and skin, by the action of cold, 

 of increased air currents, and of psychical excite- 

 ment united to the antecedent fatigue. The dele- 

 terious effects of these abnormal stimulations can 

 be lessened, or even done away with, by practice, 

 and the effect of the diminished partial pressure of 

 oxygen, which is observed in the case of some per- 

 sons, may be prevented by mixing a little (about 2 

 per cent.) of carbon dioxide with the inspired air, 

 that gas inducing deeper inspirations. 



The most generally accepted explanation of the 

 benefit which persons of weak lungs are supposed 

 to derive from mountain air is that in the rarer at- 

 mosphere of high altitudes a much more complete 

 expansion of the lungs is necessary to obtain the 

 same quantity of oxygen that would be required in 

 the denser atmosphere of the plains. Consequently 

 sojourners on mountains unconsciously acquire the 



habit of full breathing. Another source of benefit 



-'ed by a writer in the London 11 

 that, as he -ays lias r>-r.-ntly been shown, " tin- blood 

 itself becomes altered in response to ti, 

 amount of the more rarefied oxygen which each 

 blood corpuscle can carry. The elfeet of this pro- 

 cess of adaptation is that the red corpusr]e> multi- 

 ply considerably, while, as some believe, the hemo- 

 globin is also increased. This accords with the 

 well-known effect of mountain air in the treatment 

 of anemia and with the sense of well-being felt by 

 visitors to high altitudes. Other salutary factors 

 in the qualities of mountain air are its purity, drv- 

 and comparatively low temperature, combined 

 with the intense solar radiation at high altitu<: 



The anaesthetic properties of nitrous oxide have 

 sometimes been ascribed to its asphyxiating power. 

 Careful comparisons of its physiological action with 

 that of a neutral gas, such as nitrogen. G. T. Kemp 

 says, show that separate anesthetizing and asphyxi- 

 ating powers may be demonstrated in nitrous oxide. 

 To supplement this, a series of analyses of the blood 

 gases of animals asphyxiated by nitrous oxide show 

 that anesthesia may be obtained with this gas while 

 the blood is still carrying sufficient oxygen to meet 

 the demands of the system. 



Circulation. Experiments made heretofore 

 have shown that absorption by the blood vessels 

 takes place in cases where substances not occurring 

 normally in the blood are introduced into some con- 

 nective-tissue space : but the processes by which 

 this occurs do not serve to explain the absorption 

 by the blood vessels of fluids having the same 

 tonicity and the same approximate constitution as 

 the circulating plasma. Ernest H. Starling has 

 studied this subject with reference to the question 

 whether the blood vessels do absorb such isotonic 

 fluids, and that of the manner in which the absorp- 

 tion takes place. As the result of his experiments 

 he concludes that isotonic solutions can be and are 

 absorbed directly by the blood vessels; that a back- 

 ward filtration into the vessels is mechanically im- 

 possible in the connective tissue of the limbs, the 

 muscles, and the glands similar in structure to the 

 submaxillary : that the absorption is determined by 

 the osmotic pressure of the serum of the proteids 

 (from 30 to 40 millimetres mercury). The same 

 factor is probably responsible for the absorption 

 from the tissues that ensues on any general lower- 

 ing of capillary pressure, as in general anemia ; and 

 that the proteids of the tissue fluids, when not used 

 up in the tissues themselves, are probably absorbed 

 mainly, if not exclusively, by the lymphatic system. 



The results of the researches of R. M. Horne on 

 the action of certain salts in preventing coagulation 

 of the blood show that the salts of calcium, stron- 

 tium, and barium retard or prevent coagulation 

 when present in the proportion of 0'5 per cent, and 

 upward ; that barium salts have a more powerful 

 preventive action upon coagulation than strontium, 

 and strontium than calcium salts. Barium chloride 

 materially retards coagulation in the proportion of 

 0- -?."> percent. Calcium hydrate in saturated watery 

 solutions does not retard, and strontium hydrate 

 retards only slightly, while barium hydrate is highly 

 effective in retarding coagulation of the blood. The 

 delaying influenceof calcium, strontium, and barium 

 chlorides upon coagulation is overcome by dilution 

 with distilled water and by the addition of a suit- 

 able quantity of potassium oxalate. Coagulation 

 of blood treated with calcium, strontium, or barium 

 chloride is accelerated by a temperature of from 30' 

 to 40 : C. Sodium chloride and potassium chloride, 

 added to the extent of 0-07 per cent, and upward, 

 do not accelerate, but still further retard the coagu- 

 lation of the blood which has been treated with 

 calcium or strontium chloride. 



