CHAP. V.] THE LYMPH AND CHYLE. TRANSLATIONS. 227 



carbonic acid within the blood-vessels rather than in the tissues ; if, it 

 might be argued, C0 2 is formed in the tissues and passes into the 

 blood, it can only do so in virtue of the CO 2 having a higher tension 

 in the extra-vascular liquids than in the blood. The answer which 

 has been given to this objection may be summarized as follows : 

 It is conceivable, and indeed most likely, that the tension of the CO 2 

 at the seats of its formation (in and near the anatomical elements 

 of the tissues) may be much higher than that of the lymph. If 

 .instead of analysing the lymph we analyse the normal secretions 

 of the body, such as the urine, bile, saliva, &c., which result 

 more directly from the action of the anatomical elements, we shall 

 be analysing liquids whose gaseous tension will, in all probability, 

 more nearly represent that of the tissues which are the seat of the 

 respiratory combustion. Now the tension of the C0 2 of these liquids 

 is much higher than that of the lymph, and higher even than that 

 of venous blood. 



All difficulty in explaining the passage of carbonic acid into 

 the blood has, however, been removed by the last investigation on the 

 gases of the lymph made in the Leipzig laboratory. Gaule 1 has 

 determined the comparative tension of the CO 2 , of blood, lymph and 

 serum, and has shewn that whilst the quantity of that gas in the 

 serum is greater than in the lymph, the tension of the C0 2 is 

 much greater in the lymph than in the serum. The same difference 

 will doubtless hold between the tension of the lymph and the tension 

 of the liquor sanguinis, and as we may consider the exchange of CO 2 

 to occur in the first place between those two liquids, its passage into 

 the blood is easily accounted for. 



The following are the results of one of Gaule's experiments : 



PEECENTAGE OF C0. 2 , AND TENSION OF THE GAS, IN THE BLOOD- 

 SEEUM AND LYMPH OF AN ASPHYXIATED DOG. 



C0 2 in 100 vols. Tension in mm. of Mercury. 



(Temp. 40 C.) 



Blood 24-6 567 



Serum 34'5 33'4 



Lymph 25%5 521 



This subject will again be referred to at length in discussing the 

 Respiration of the Tissues. 



1 Gaule, "Die Kohlensaurespannung im Blut, im Serum und in der Lymphe." 

 Ludwig's Arbeiten, 1878, and Archiv fur Physiologic of Du Bois-Keymond, 1878, p. 469. 



152 



