xx CONTENTS. 



PAGE 



249. The course taken by sugar 414 



250. The course taken by proteids 415 



The Mechanism of Absorption. 



251. The mechanism of the absorption of the fats 417 



252. The pumping action of the villi 419 



253. The mechanism of the absorption of diffusible substances and of 

 water. Relations of the process to diffusion. Action of the 

 cells. The two stages of the act of absorption ; their nature . 420 



CHAPTER II. 

 254. Respiration 424 



SECTION I. 

 THE MECHANICS OF PULMONARY RESPIRATION. 



255. The entrance and exit of air into and from the lungs ; tidal and 



stationary air 425 



256. Complemental, reserve or supplemental, and residual air. Results 



of an opening into the pleural chamber 426 



257. The lungs before birth and the changes at birth . . . .4^7 



258. The pressure exerted in breathing and the quantity of air moved . 427 



259. The graphic records of the respiratory movements ; pneumatograph 428 



260. The curve of respiratory movements 432 



The Respiratory Movements. 



261. The visible movements .433 



262. The movements of inspiration. The movements of the diaphragm 433 



263. The elevation of the ribs 434 



264. The muscles which move the ribs 435 



265. The muscles of laboured inspiration 436 



266. Expiration. The expiratory muscles 437 



267. Facial and laryngeal respiration 438 



SECTION II. 



/ 

 THE CHANGES OF THE AIR IN RESPIRATION. 



268. The changes in temperature 440 



269. The aqueous vapour in expiration 440 



270. The gaseous changes 440 



271. The diminution in volume . . . 441 



272. The organic impurities in expired air 442 



SECTION III. 



THE RESPIRATORY CHANGES IN THE BLOOD. 

 273. The gases of arterial and venous blood. The mercurial gas pump . 



