CHAP. II.] THE BLOOD. 103 



specimens of tincture of guaiacum. This blueing of the resin of 

 guaiacum is due to its oxidation and is also observed when ozone acts 

 upon it, but not when common oxygen does so. 



When the respiratory oxygen of haemoglobin has been expelled 

 from blood by the action of carbonic oxide, as will be afterwards 

 described at length, it no longer possesses (in the absence of oxygen) the 

 power of blueing guaiacum. If atmospheric oxygen, however, comes 

 in contact with the drop of CO blood and guaiacum, the blue ring 

 appears. 



Oxy-haemoglobin shares with many other organic bodies and also 

 with many inorganic bodies, such as spongy platinum, the power of de- 

 composing hydrogen peroxide, H 2 O 2 , as is proved by the effervescence 

 produced in a solution of the latter by the addition of a few drops 

 of blood or of a solution of haemoglobin ; if to a mixture of blood and 

 tincture of guaiacum some solution of H 2 O 2 be added, the fluid 

 assumes a blueish tint. 



Does the These facts were formerly explained by A. Schmidt 



oxygen of on *he hypothesis that haemoglobin possesses in an 



oxy-haemo- intense degree the power of ozonizing oxygen and of 

 giobin possess rendering it therefore infinitely more active than atmo- 

 spheric oxygen. Against this view Pfliiger 1 has raised 

 the most serious, and it appears to us the most reason- 

 able objections, which will have to be considered in detail in another 

 section. According to Pfliiger when blood is poured upon filter paper, 

 as in the guaiacum experiment previously referred to, the haemoglobin 

 almost instantly undergoes decomposition, and it is the products of 

 decomposition which occasion the reaction. According to Pfliiger 

 haemoglobin in no way modifies the properties of the oxygen which 

 it links to itself. 



Proportion I n former times, when blood-letting was highly 



ofhaemogio- prevalent, a large number of analyses of blood were 

 bin in the made by competent observers who had no means, such 



blood of man. ag we now p OSSesSj o f determining directly the amount 

 of haemoglobin, but who ascertained the amount of iron contained in 

 the blood. Since we now know the exact proportion of iron which 

 haemoglobin contains, we may calculate the amount of this substance 

 found by the older observers. Preyer 2 has taken the trouble to do 

 this in the case of a large number of the most reliable analyses, and 

 from his tables we take the following extract: 



QUANTITY OF IEON AND HAEMOGLOBIN COEEESPONDING TO IT 

 CONTAINED IN 100 GEMS. OF BLOOD. 



A. Blood of woman (in health). 



Iron. Hamoglobin. 



Minimum . . . OO48 gnu. ll'57grm. 



Maximum . . . 0-057 13'69 



1 E. Pfliiger, " Kritik iiber die Angaben vom Ozon im Thierkorper/' Pfluger's 

 Archiv, Vol. x. p. 252. 



3 Preyer, Die Blutkrystalle, p. 117, et seq. 



