524 APPENDIX. 



paration of the crystalline substance ; although it would require far 

 more extended investigations to exhibit the true mode of their 

 operation. It would, however, be going too far, were we to con- 

 clude that the property which a protein-body exhibits of being 

 modified in its character by oxygen and carbonic acid, is anything 

 peculiar to this substance, or is any special attribute appertaining 

 to this constituent of the blood- corpuscles. For, independently of 

 the fact that, as we have already mentioned (see page 495 of this 

 volume), globulin can be completely precipitated from its neutral 

 solutions by carbonic acid, and the precipitate can be again dis- 

 solved by a stream of oxygen, certain modifications of the crystalline 

 substance occur, which stand in precisely the reverse relation to these 

 gases. I have described in p. 489 of this volume that modification 

 of the crystalline substance which can be exhibited by acetic acid 

 and an alkaline salt, and which corresponds with Panum's acid 

 albumen (see page 478). When the faintly acid solution of 

 this product of metamorphosis is carefully neutralised with a very- 

 dilute solution of potash, the substance will be perfectly precipi- 

 tated ; but this precipitate dissolves again in pure water, although 

 not to any great extent, forming a pale red solution, from which 

 the substance may be so completely thrown down by oxygen or 

 by the action of the air, as only to leave a perfectly colourless 

 fluid over the dirty flesh-coloured precipitate. On passing a 

 stream of carbonic acid through this fluid, the precipitate re- 

 dissolves into a pale red fluid. The substance may be again pre- 

 cipitated by oxygen, while the solution coagulates on boiling, in 

 the same manner as albumen. These experiments, nothwithstand- 

 ing their isolated character, contribute, together with what we have 

 already stated in the last page, in reference to the influence of the 

 gases upon the formation of the blood-crystals, to strengthen the 

 probability that a chemical action may be impressed upon the main 

 constituent of the blood-corpuscles by the .alternating action of 

 oxygen and carbonic acid, although opinions may differ as to 

 whether this is manifested by an oxidation or a reduction, or 

 whether it arise from the simple occurrence of carbonic acid as a 

 conjugated acid, or finally, whether it be referrible to a salt-like 

 compound. 



Here I cannot refrain from observing that the substance corre- 

 sponding to the acid albumen has not fallen under my notice as a 

 product of decomposition of the true crystallisable matter of the 

 blood, although Panum is of opinion that the albumen may be 

 decomposed by acids and potash-salts into acid albumen and into 



