148 PEACTICAL PHYSIOLOGY 



by small meters. The following figures show the effect of diet, rest, 

 and work on the respiratory exchange of man. 



C0 2 . 0* 



Day. Night. Day. Night. 



Fasting : .Rest, - ... 403 grms. 314 grms. 435 grms. 326 grms. 



,, Work for nine hours, 930 ,, 257 ,, 922 150 ,, 

 Moderate diet : Rest, - 533 395 443 449 

 Work for nine hours, 856 353 795 , 211 



CHAPTER XLI. 

 GASES OF THE BLOOD, 



Analysis of the Gases of the Blood by Hill's Pump. 1 The pump 

 consists of a mercury reservoir A, which is connected with a second 

 reservoir B by means of pressure tubing. The upper end of B is 

 closed by a three-way tap. By means of this tap B can be put in 

 connection with either the tube E leading to the blood-receiver F, or 

 with the tube C leading to the eudiometer H. The blood-receiver F 

 is constructed of three bulbs, so as to prevent the blood frothing over 

 into B during the extraction of the gases. To either end of F is fixed 

 a piece of thick small-bored pressure tubing provided with a clip. 



In using the pump the manipulations are as follows : F is placed 

 in the position indicated by the dotted line. A is raised and B is put 

 in connection with F, and F is filled with mercury. The screw clip on 

 the rubber tube at the upper end of F is then closed, and A lowered 

 until F is exhausted, except for 2 or 3 c.c. of mercury which are 

 purposely left within. 



The screw-clip on the lower end of F is next closed, and F is then 

 detached from the pump and weighed. A sample of blood is collected 

 in the following way : The arterial or venous cannula is filled with 

 blood, and immediately pushed into the rubber tube at one end of F. 

 Before the insertion of the cannula the end of the rubber tube is 

 compressed with the fingers to exclude the air within it. A sufficient 

 quantity of blood is now withdrawn by opening the screw-clip, and the 

 clip placed on the vessel of the animal. The blood is defibrinated by 

 shaking it with the mercury left within F for the purpose. F is then 

 again weighed, and the weight of the sample obtained. F is next affixed 

 to the tube E, and ,E is exhausted. Finally the screw-clip between E 

 and F is opened, and the gases are withdrawn and collected in the 



1 Many blood-gas pumps have been contrived. Pfliiger's is one of the best. A 

 very accurate pump is that of Barcroft (cp. Journ. of Physiol. xxv. 265). 



