CONNECTION BETWEEN BLOOD AND ITS GASES. 771 



Setschenow 1 calculated that serum held in simple solution 99 per 

 cent, of the amount of carbon dioxide which distilled water would 

 absorb under similar conditions, and that one-tenth of the total carbon 

 dioxide in the serum of dog's blood was in simple solution. The result 

 of further experiments made by Zimtz 2 upon these points is shown in 

 the table on p. 770. 



In the next place, it is necessary to consider the amount of carbon 

 dioxide in loose and firm chemical combination with substances in the 

 corpuscles, plasma and serum. Most of the gas is contained in the 

 plasma or serum, for these fluids contain a larger quantity of carbon 

 dioxide than that which can be obtained from an equal volume of blood. 

 The greater quantity of the gas is in a state of loose chemical combination 

 in the serum, for much of it can be extracted by the action of the 

 vacuum of a blood-pump ; the remainder, however, is in firm chemical 

 combination, and is only set free in the pump by the addition of an 

 acid. In this respect a marked contrast is observed between blood and 

 serum, for all the carbon dioxide can be extracted from the former by 

 the action of the vacuum alone, the haemoglobin of the red corpuscles 

 playing, apparently, the part of an acid.-'' 



The following table shows the amount of carbon dioxide in loose and 

 firm chemical combination in serum : 



The differences in these results are due, as Zimtz 7 has pointed out, 

 to the powerful action of Pfliiger's pump, and to the concentration of the 

 serum during its exposure to the vacuum. The carbonates of the serum give 

 off their gas more readily when the solution is concentrated ; this complication 



1 Loc. cit., CentralN.f. d. mecL Wissensck., Berlin, 1877, No. 35. 



2 Hermann's "Handbuch," Bd. iv. Th. 2, S. 68. 



3 Setschenow, Sitsungsb. d. k. Akad. d. Wissensch., Wien, 1859, Bd. xxxvi. S. 293; 

 Pfliiger, " Ueber die Kohlensaure des Blutes," Bonn, 1864, S. 5 ; Zuntz, CentralbL f. d. 

 med. Wissensch., Berlin, 1867, S. 527. 



4 Sitzungsb. d. k. Akad. d. Wis*cnsch. Math.-naturw. CL, Wien, 1860, Bd. xli. S. 616. 



5 "Ueber die Kohlensaure des Blutes," Bonn, 1864, S. 11. 



6 Centralbl. f. d. med. Wissensch., Berlin, 1867, S. 529; Hermann's "Handbuch," 

 Bd. iv. Th. 2, S. 45. 



7 Loc. cit. 



