RESPIRATION xv 



on the urine excreted during forced breathing, 195. True acidosis caused by 

 excessive muscular exertion, 196. Disturbance of blood reaction in nephritis, 

 196. Ammonium chloride acidosis in man, 196. Remarks on indirect methods^ 

 used for measuring changes of reaction in the blood, 199. Method depending 

 on the dissociation curve of oxyhaemoglobin, 199. Method depending on ratio 

 of combined CO 2 to free CO 2 in blood, 200. Need for more delicate methods 

 than we possess at present, 202. Question as to the constancy of blood reaction 

 during normal life, 202. Action of drugs on the regulation of blood reaction, 

 204. Reasons why the alveolar CO2 pressure is not perfectly steady during 

 rest, 204. Effects of meats, 204. Effects of starvation and carbohydrate-free 

 diets, 205. The regulation of breathing in man during rest is practically 

 speaking regulation of blood reaction, 205. Addendum. Recent literature on 

 acidosis and alkalosis, 205. Definition of acidosis and alkalosis, 206. Ex- 

 treme delicacy and physiological importance of regulation of reaction in the 

 tissues, 207. 



CHAPTER IX. GAS SECRETION IN THE LUNGS . . 208 



Question as to active secretion of gas by the lung epithelium, 208. Oxygen 

 secretion by the swim bladder epithelium, 208. Function of the swim bladder, 

 208. Biot's discovery of oxygen secretion, 209. Experiments of Moreau, Bohr, 

 and Dreser, 210. Jager's discovery of the "oval" in the swim bladder, 211. 

 Histology of the swim bladder wall and "red body," 214. Probable function of 

 the "red body," 214. Gas secretion in Arcella. Experiments of Bles, 216. 

 Implications of secretion generally, 217. Ideas of Johannes Miiller on secre- 

 tion, 218. -Apparent gas secretion in Corethra larvae, 220. Ludwig and 

 Pfliiger on gas secretion by the lungs, 220. Experiments of Bohr and Fredericq, 

 221. Method and experiments of Krogh, 222. Carbon monoxide method of 

 measuring arterial oxygen pressure, 224. Fallacies in earlier measurements, 

 225. New experiments on animals. Conclusions, 226. New experiments on 

 men. Method, 229. Result that secretion is completely absent during rest 

 under normal conditions, but present under conditions producing want of oxy- 

 gen in the tissues, 233. Experiments after acclimatization on Pike's Peak, 236. 

 Evidence of constant active secretion, 237. Indirect evidence of oxygen 

 secretion, 238. Experiments of Briggs, 240. Experiments in a respiration 

 chamber at normal atmospheric pressure, 241. Acclimatization experiments in 

 a steel chamber, 242. Cause of difference between results by carbon monoxide 

 and aerotonometer methods, 243. Reason why the percentage of oxygen satura- 

 tion of the arterial blood is considerably less at high altitudes before acclimatiza- 

 tion than corresponds to the oxygen pressure of the alveolar air, 244. Bohr's 

 method of measuring the rate of diffusion of gases from the alveolar air into 

 the blood, 245. Experiments of A. and M. Krogh by this method, 246. 

 Paralysis of oxygen secretion under pathological conditions, 247. Direct evi- 

 dence that during hard muscular work at normal atmospheric pressure diffusion 

 of oxygen is quite insufficient to saturate the arterial blood with oxygen, 247. 

 Question of active excretion of COa by the lungs. Krogh's experiments, 247. 

 Reasons for suspecting that active secretion of COa may occur under certain 

 conditions, 248. Comparison of oxygen secretion by the lungs with glomerular 

 secretion by the kidneys, 250. Reply to some recent criticisms of the evidence 

 for oxygen secretions, 251. Addendum. Recent experiments of Barcroft and his 

 co-workers, 253. 



