THE BLOOD. 1 15 



The same is the case, according to Henle, after treatment 

 by nitric acid. 



The acetic, and one or two other acids, it is known, dis- 

 solve the corpuscles of the mammalia without residue, but 

 leave almost unaffected the granular nucleus contained in the 

 red blood corpuscles of the oviparous vertebrata. 



The above are some of the more striking effects produced 

 in the form, colour, and constitution of the blood corpuscles 

 out of the system, on their treatment by reagents. 



Now there is evidence to show that blood corpuscles, while 

 they are circulating in the body, are likewise affected, 

 although to an extent less considerable, and therefore less 

 appreciable, by substances and solutions introduced into the 

 system through the medium of the lungs or of the stomach. 



Thus we know that the blood changes its colour in the 

 lungs and during its circulation through the capillaries, and 

 that these changes are dependant upon the relative amount 

 of oxygen and of carbon contained in the corpuscles. 



Again, it has been asserted by Schultz, as already men- 

 tioned, that accompanying these alterations of colour there 

 are also changes of form, the corpuscles becoming more or 

 less circular in carbonic acid and hydrogen gases, and flat in 

 oxygen gas. This assertion I have myself failed to verify. 



It cannot be doubted, however, but that the form of the 

 red blood corpuscle must vary according to the variations of 

 density experienced by the liquor sanguinis, and further but 

 little hesitation can be felt in admitting that this alteration 

 of density does really attend upon particular conditions of 

 the system ; thus, in inflammatory affections, the liquor 

 sanguinis is assuredly more dense than it is in states in which 

 in opposite condition of the blood exists, that in which the 

 watery element abounds. 



After very copious imbibition of water also, it can scarcely 

 be doubted but that the density of the blood is lessened, and 

 that the red corpuscles are modified in shape in conse- 

 quence. 



Thus much for colour and form ;. let us see if we are 

 acquainted with any fact capable of proving that the con- 



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