190 BLOOD. 



We have seen that the blood-corpuscles obtained from the 

 hepatic veins contain less peroxide of iron than those from the 

 portal vein. Schmidt found an excess of iron in the blood- 

 cells in hydrsemic conditions,, and hence he concludes that in 

 these cases the blood-cells have become poorer in globulin, but not 

 richer in haematin; he believes, however, that we may calculate the 

 hsematin from the quantity of iron found in the ash; and this 

 conclusion certainly seems justifiable if we had to do with the 

 pure hsematin of the chemist, which contains 6'6 of iron ; but 

 we must take into consideration that the hsematin, in all probability, 

 does not start, Minerva-like, into perfect being, but that, almost to 

 a certainty, it is gradually formed, even as it is gradually destroyed ; 

 to which it must be added that we are already acquainted with 

 (artificially prepared) non-ferruginous hsematin ; and how, then, 

 can we tell whether, in some organ or other, we may not discover 

 hsematin either altogether free from iron or, at all events, poor in 

 that constituent ? 



Schmidt has convinced himself, by several series of experi- 

 ments, that the clear serum of the blood of oxen, sheep, swine, 

 horses, dogs, cats, rabbits, and hens, is perfectly devoid of iron. 

 (Nasse had previously found this to be the case.) 



In 100 parts of dry blood-corpuscles (determined according to 

 the method of Prevost and Dumas) Schmidt found the following 

 proportions of iron : in man, 0'4348 ; in the ox, 0*5 09 ; in the 

 pig, 0'448% ; and in the hen, 0'329. 



The gases of the blood, carbonic acid, nitrogen, and oxygen, 

 are also for the most part contained in the blood-corpuscles. It 

 has been ascertained by Davy, Nasse, Scherer, van Enschut, 

 Magnus, and others, that the serum possesses in a far less degree 

 than the defibrinated blood the capacity of absorbing oxygen and 

 carbonic acid, and I have convinced myself that at least twice as 

 much air is developed from a volume of whipped air in vacuo as 

 from an equal volume of serum that has been strongly stirred or 

 shaken with atmospheric air. Van Maackhas found that a solution 

 of hsematin possesses a decided power of attracting oxygen ; and 

 Scherer has not only convinced himself of the accuracy of this 

 observation, but at the same time ascertained that a little carbonic 

 acid is developed after the absorption of the oxygen. 



Davy and Berzelius believed at one time that they had con- 

 vinced themselves of the presence of free gases in the blood, but 

 subsequently retracted this view ; after this period, the results of 

 different experimentalists were -very discordant, some being in 



