434 



SCIENCE 



[N. S. Vol. XLIS. No. 1271 



caused by the forcible application of a 

 hard object to the org'an in qiiestion. 



The only idirect effects of changes of 

 pressure are those "which are felt in the 

 ears, and occasionally in the sinuses con- 

 nected with the nose. The ear drums are 

 connected with the throat and contain air 

 at the prevailing pressure. If the pressure 

 is lowered this air expands, and forces its 

 way out through the Eustachian tubes into 

 the throat. If the outside pressure is in- 

 creased, it sometimes happens, particularly 

 wihen the subject has a cold and the Eusta- 

 chian tubes are inflamed, that air does not 

 pass readily into the middle ear. Accord- 

 ingly the tymipanic meonlbranes are forced 

 inward by the pressure ; and this may cause 

 acute pain. Workers in compressed air 

 are accustomed, while going "into the air," 

 i. e., into pressure, to hold their noses and 

 blow at frequent intervals as a means for 

 expanding the ear drums. Aviators even 

 during very rapid descents are generally 

 relieved by merely swallowing. 



To sum up all that has been said thus 

 far, the influence of low barometric pres- 

 sure is not mechanical but chemical. Life 

 is often compared to a flame ; but there are 

 marked differences, depending upon the 

 peculiar affinity of the blood for oxygen. 

 A man may breathe quite comfortably in 

 an atmosphere in which a candle is ex- 

 tinguisihed. The candle wUl bum with 

 only slig'htly diminished brightness at an 

 altitude at which a man collapses. The 

 candle is affected by the proportions of 

 oxygen and nitrogen. The living organism 

 depends solely upon the aJbsolute amount of 

 oxygen — its so-called partial' pressure. 



Unlike the flame, a man may become ac- 

 climatized to a change of atmosphere in the 

 course of a few days or weeks. He is thus 

 adjusted to the mean barometric pressure 

 under which he Hves. Every healthy per- 

 son is so adjusted, New Yorkers to a mean 



barometric pressure of 760 mm. no less 

 than the inhabitants of Denver or Cripple 

 Creek to their altitudes. Even your tall 

 buildings could probably be shown to exert 

 a slight climatic effect upon the tenants of 

 the upper stories. The study of the pro- 

 cesses involved in such acclimatization 

 affords us one of the most promising means 

 of analyzing some of the fundamental 

 problems of life. In fact, is not the gas- 

 eous interchange of protoplasm, the carbon 

 and oxygen metaibolism of the cell, the 

 central fact of life? Is not the mode of 

 regulation of the interior environment of 

 the body — the constants of the "humours" 

 — ^the prime problem of the "vegetative" 

 side of physiology. 



Among the ill effects of lack of oxygen 

 we may distinguish three more or less dis- 

 tinct conditions. They are comparable, in 

 terms of more common disorders, to acute 

 disease in contrast with chronic conditions 

 of various degrees. Thus any one suddenly 

 exposed to acute deprivation of oxygen, as 

 is the balloonist or the aviator in very lofty 

 ascents, sholws one set of symptoms. If the 

 exposure is less acute, as in the case of one 

 taking up residence on a high mountain, 

 the effects develop gradually ; he • passes 

 through the stages of mountain sickness, 

 a condition much like sea sickness, to a 

 state of acclimatization and renewed 

 health. If however the ascent or the 

 flight is for only two or three hours, a 

 period too short for any degree of acclima- 

 tization to develop, and this strain on the 

 oxygen-needing organs is repeated daily, 

 as is the case with the a^^dator of the up-per 

 adr, the condition of "air staleness" is 

 likely sooner or later to result. It is the 

 effect of repeated slight oxygen deficiency 

 on an individual who does not become ac- 

 climatized. It is, I believe, closely related 

 to those effects of repeated over-exertion 



