ADVANCED DEMONSTRATIONS 



399 



quantity to form sodium bicarbonate. 1'246 grms. C0 2 = 632 c.c. at 

 0\ and 760 mm. = 63 vols. per cent. The bases of the blood are 

 shared among the acids proteids, chlorine, phosphoric acid, and 

 carbonic acid, according to the influence of the mass. No acid in 

 solution is combined with the bases present in that solution to the 

 complete exclusion of other acids also present in the solution. The 

 acids share the bases according to their avidity. The introduction of 

 any salt, acid, or base into the solution upsets the condition of equili- 

 brium, and a new distribution of the acids and bases occurs. In the 

 tissues the mass influence of C0 2 is considerable, 

 while in the lungs it is slight. The kind of change 

 which may occur when the blood passes through 

 the tissues is indicated by the following equation: 

 Na 2 HP0 4 + C0 2 H 2 O = NaHC0 3 + NaH 2 P0 4 . The 

 intra- venous injection of acid in rabbits rapidly lessens 

 the carrying power of the blood for C0 2 . In car- 

 nivora the injected acid is to a considerable extent 

 neutralised by the salts of ammonia- the precursors 

 of urea. 



Fredericks Aero tonometer. DEMONSTRATION OF 

 METHOD. The wide tube is filled with a known 

 mixture of gases, say N84 and 2 16. It is sur- 

 rounded with a water jacket through which water 

 at body temperature is circulated. The narrow 

 tube is connected with a cannula in the carotid 

 artery, and the wide tube with the jugular vein. 

 The blood is allowed to flow up the narrow tube 

 and down the wide tube, where it is exposed in a 

 thin film to the atmosphere. The blood is prevented 

 from clotting by a previous injection of leach extract. 

 After the blood has circulated a sufficient time to 

 allow equilibrium between the tension of the gases 

 in the blood and in the wide tube, the circulation 

 is stopped, and the contents of the wide tube 

 analysed. If 14 vols. per cent, of O 2 are now 

 found in place of 16, the tension of 2 in the blood is taken as 14 

 per cent, of an atmosphere. The alveolar air is collected by means 

 of a byway cannula introduced into a bronchial tube (Pfliiger's lung 

 catheter). One of the tubes terminates in a rubber bag, which is 

 expanded so as to block the bronchial tube. Through the other 

 tube the air in the lobe is withdrawn for analysis. The analysis 

 may be carried out by Haldane's gas analysis apparatus. Fredericq 



