168 Chapter X 



We wish to find p' in the first period, in which p is represented by 

 by T,. 



Q\ ' Qz '' GI~ T! : G 2 T o, 



025 



but d = 61, .'. ^ = 43. 



On the assumption that T 7 . = 0, T = 43, the extra-capillary pressure 

 cannot be less than 43 mm. But also 7\ cannot be more than 43 for 

 this is the venous pressure, and by a reversal of the above calculation 

 To cannot then be more than zero. It appears therefore that within the 

 limits of experimental error the line T^ T 2 does represent the extra- 

 capillary or tissue oxygen pressure, and that this almost coincides 

 with the oxygen pressure in the vein, so that the blood has nearly 

 got into equilibrium with the tissue before it leaves the gland. 



The other two experiments tell the same story. The oxygen 

 pressure in the tissue is, within the limits of experimental error, equal 

 to that in the venous blood. So far from the intra-cellular oxygen 

 pressure being nil, as it is usually stated to be in elementary books on 

 physiology, it is rather considerable, over 40 mm. in each of the three 

 experiments cited. 



Herein lies the importance of this fact : if the intra-cellular pres- 

 sure is 40 mm. with a certain value for Q, there is room for it to 

 fall down to zero, in which case the pressure gradient would increase 

 from 18 mm. to 61 mm., providing for a corresponding increase in the 

 value of Q should the cells demand it. 



We have no corresponding data unfortunately with respect to the 

 active submaxillary gland ; so the submaxillary story must end here. 



We pass to skeletal muscle ; the experiments are not so uniform, 

 nevertheless they seem to justify certain positive conclusions. I will 

 take the two extreme (Exps. V and VII in Verzar's paper) cases as 

 examples because they are satisfactory inasmuch as the blood flow 

 in each remained fairly constant. The first one for consideration is 

 Exp. V(Fig. 90). In this the values of d and (7 2 were 43 and 19 mm. 

 respectively. Let us endeavour again to ascertain the value of 7\ by 

 assuming that T 2 is nothing. 



Q! = '043, Qo = '016 c.c. per min., <7 2 - T. = 19 mm., 



A4.Q 



/. d-7^19 x i = 50mm. 

 DID 



