630 PHYSIOLOGY OF RESPIRATION. 



etc. At certain altitudes, from 3000 to 4000 meters, disagreeable 

 symptoms are experienced by many persons, especially after 

 muscular effort, which are designated usually under the term 

 mountain sickness. The individual so affected suffers from head- 

 ache, nausea, vertigo, great weakness, etc. Much investigation, 

 especially of recent years, has been devoted to this subject.* Paul 

 Bert concluded, from his numerous experiments, that a fall in baro- 

 metric pressure acts upon the organism only in so far as there is a 

 diminution of the partial pressure of the oxygen in the air respired. 

 This view has been generally accepted in physiology, and mountain 

 sickness and similar disturbances in balloon ascents have been 

 explained, therefore, as due mainly to the lack of oxygen, that is, 

 to the condition of anoxemia. Mosso, on the contrary, has insisted 

 upon the part played by the carbon dioxid. He gives experi- 

 ments to show that there is a diminution in the carbon dioxid 

 contents of the blood (a condition of acapnia), and it is to this, 

 rather than to the anoxemia, that he would attribute the physio- 

 logical results of low barometric pressures. Other authors lay 

 stress upon the mechanical disturbances of the lung circulation, 

 while still others assume that certain vaguely understood cosmical 

 influences such as the electrical condition of the air, its ioniza- 

 tion, or radiations of some kind may affect the metabolisms of 

 the body and thus produce the symptoms in question. It would 

 seem that the whole matter is more complex than was at first 

 supposed. At a height of 4000 meters, at which mountain sick- 

 ness is apt to occur, the barometric pressure is 460 mms., so that 

 there is an oxygen pressure of 92 mms., a pressure high enough, 

 one would suppose, not to endanger the oxygen supply. Mosso 

 states, also, from experiments upon monkeys, that lowering the 

 barometric pressure sufficiently (to about 250 mms.) causes un- 

 consciousness (sleep) even when the partial pressure of the oxygen 

 is kept normal. The historical incident of the death of Sivel and 

 Croce-Spinelli at an altitude of 8600 meters (barometric pressure, 

 262 mms.; oxygen pressure, 52.4 mms.) seems to indicate also that 

 something more than mere diminution in oxygen pressure is respon- 

 sible for the effects of extremely high altitudes. 



The incidents connected with the ascent in the balloon Zenith of Sivel, 

 Croce-Spinelli, and Tissandier, April 15, 1875, are described in detail by the 

 last named in "La Nature," 1875, p. 337, also in Bert's "La pression baro- 

 metrique," p. 1061. Only Tissandier survived. The balloonists were pro- 

 vided with bags containing oxygen (72 percent.), but they were unable to 

 make satisfactory use of it, since shortly after passing 7500 meters they be- 

 came so weak that the effort to raise the arm to seize the oxygen tube was 



* See Kronecker, " Die Bergkrankheit," Berlin, 1903. Mosso and Marro, 

 " Archives italiennes de biologic, " 39, 387, also vols. 40 and 41. Cohnheim, 

 article on " Alpinismus, " " Ergebnisse der Physiologic," vol. ii, part i, 1903. 



