227 



a, is set aside in a receptacle of known capacity. The animal is then 

 thoroughly bled, and its vascular channels washed out with normal 

 saline. To avoid errors, the urinary and biliary bladders are removed. 

 The different organs and tissues are then finely divided and thoroughly 

 extracted with saline. This mixture (6) is subsequently diluted, until 

 its color corresponds precisely to that of solution a when placed in 

 the same kind of receptacle. If the volume of solution b is now divided 

 by 500, the quotient indicates how many times the quantity of blood 

 contained in solution a is contained in solution 6. 



The first attempt to determine the quantity of blood in a chemical manner 

 has been made by Grehant and Quinquaud. 1 Having ascertained the volume per 

 cent, of oxygen in a given sample of blood, the animal was permitted to breathe a 

 known volume of carbon monoxid. The total amount of CO was then deter- 

 mined and also the volume per cent, of O in a second sample of blood. The 

 difference in the volume per cent, of O in the two samples corresponds to the volume 



per cent, of CO in the blood, because CO displaces an equal volume of O. The total 



y 

 quantity of blood is calculated according to the formula - X 100; V stands 



for the total amount of CO absorbed by the blood, and v for the volume per cent. 

 of CO, i.e., for the number of cubic centimeters of this gas for each cubic centi- 

 meter of blood. 



The method of Haldane and Smith 2 is based upon a similar principle. It 

 depends upon the displacement of the oxygen from oxyhembglobin by carbon mon- 

 oxid. If a person is permitted to inhale a definite volume of CO, and if it is then 

 found by means of a hemoglobinometer that % of the hemoglobin of his blood 

 has been saturated with this gas, it may be concluded that five times this amount 

 is needed to charge all of his blood. In this way we ascertain what might be called 

 the carbon monoxid capacity of the blood. We know that the amount of CO 

 in CO-hemoglobin is identical with the amount of O contained in O-hemoglobin, 

 and hence, the above value also indicates the oxygen capacity of the blood. Know- 

 ing the latter, the amount of hemoglobin present in the body can easily be as- 

 certained, and knowing the percentage amount of the latter, the total volume 

 of the circulating blood can thereupon be calculated. 



To illustrate: A certain person exhibits the color of the 100 percent, stand- 

 ard and possesses therefore a capacity of 18.5 c.c. of oxygen per 100 c.c. of blood. 

 If, after the inhalation of 75 c.c. of carbonic oxid gas, his blood is found to be 

 saturated with this gas to the extent of 15 per cent., an equal per cent, of the 

 18.5 c.c. must be present as carbon monoxid, namely, 2.7 c.c. Consequently, 

 if 2.7 c.c. of carbon monoxid are present in 100 c.c. of blood after breathing 75 c.c. 

 of this gas, it only remains to be determined how much additional gas must be 

 inhaled in order to give the value of 18.5. 



Thus, 2.7 c.c. per 100 c.c. of blood on inhalation of 75 c.c. of CO 



75 



1.0 c.c. per 100 c.c. of blood on inhalation of =-^ c.c. of CO 



2i. i 



and 18.5 c.c. per 100 c.c. of blood on inhalation of c.c. of CO 



mi 



This implies that the total oxygen capacity is 500 c.c. As 18.5 c.c. of this amount 

 are contained in 100 c.c. of blood, the total volume of blood which will carry 500 



500 X 100 

 c.c. of the gas is: -TQ~K~~ = 2727 c.c. The total weight of this mass of blood 



is ascertained by multiplying the volume with the specific gravity. 



1 Compt. rend., vii, 1883. 



2 Jour, of Physiol., xx, 1896, 295, and xxv, 1900, 497. 



