356 VEHICLES OF CHEMICAL CORRELATION 



from the decomposition of chlorophyll, a substance, Phyloporphyrin, 

 is obtained which differs from hematoporphyrin only in containing 

 two hydrogen atoms in the place of two hydroxyl-groups. The attempt 

 has been made to transform hematoporphyrin into phyloporphyrin 

 by reduction, but this attempt has as yet only been partially successful, 

 only one of the hydroxyl groups in hematoporphyrin having been 

 replaced by hydrogen. 



The close relationship of hematin to chlorophyll at once suggests 

 the possibility that the necessary radicals for the binding of hemo- 

 globin may be obtained by animals from the decomposition-products 

 of chlorophyll. The pyrrole grouping may of course be obtained from 

 the Proline and Oxyproline constituents of the protein molecule, but it is 

 a question whether the synthetic activity of the hemopoietic tissue 

 in the red marrow of the bones goes so far as to build up hsmatin 

 from pyrrole or whether, rather, somewhat more complex fragments 

 of hematin may not be requisite. It is true that chlorophyll is not 

 digestible by the hydrolytic enzymes of our alimentary system, but 

 that does not exclude the possibility of bacterial digestion in the lower 

 intestine, and as a matter of fact, Marchlewski has shown that chloro- 

 phyll does actually in part disappear when introduced into the aliment- 

 ary canal of animals. Abderhalden has suggested that the failure of 

 inorganic-iron therapy in certain cases of Anemia may be attributable 

 to lack of certain decomposition-products of chlorophyll in the diet, 

 or to lack of the proper assimilation or utilization of these products 

 which he conceives, may be necessary for the synthesis of hemoglobin. 



THE CRYSTALLINE FORMS OF HEMOGLOBIN IN RELATION TO 

 THE BIOLOGICAL INDIVIDUALITY OF THE BLOOD. 



The constant percentage of iron in the hemoglobins derived from 

 different Vertebrata invites, but does not establish the accuracy of the 

 supposition that the hemoglobins from different sources are identical. 

 While the quantitative composition of hemoglobin must be the same 

 in all species, yet there exist a very large number of conceivable ar- 

 rangements of the various radicals and groupings in the molecule, and 

 of stereochemical differences not detectable by mere analysis. In fact 

 Reichert and Brown have in recent years very strongly advocated 

 the view that the hemoglobin of every species differs chemically or 

 stereochemically from that of every other, basing their view upon the 

 results of their monumental investigation of the crystalline forms of 

 hemoglobin derived from different sources. 



Crystals of hemoglobin are readily obtained from the blood of cer- 

 tain animals by the mere evaporation of blood "laked" by ether. This 

 procedure suffices in the case of the blood of the rat, for example. In 

 many cases it is necessary to cool the blood to zero and in some to add 

 alcohol to reduce the solubility of the hemoglobin. Generally speaking 

 the best method to induce crystallization is to add from one to five 



