BLOOD AND LYMPH. 567 



the food has undergone a more or less complete preliminary disintegration. 

 The fact that large amounts of decomposition products of chlorophyll are 

 found in the faeces of herbivora, does not in any way speak against the 

 above assumption. We unfortunately know nothing regarding the extent to 

 which hematin is destroyed and newly formed in the animal organism. In 

 the yolk of eggs, and also in the vegetable kingdom, we meet with nuclein- 

 like substances which, as we have said, are very similar in their elementary 

 composition to hemoglobin. It is indeed possible that these substances 

 are used as the raw materials for the hematin synthesis. We do not in 

 any case need to assume that the animal cell accomplishes the complicated 

 construction of hemochromogen from simple building material. We only 

 wish to sound another warning against drawing any conclusions from the 

 elementary composition of such complicated products. The formation of 

 hemoglobin, and especially of hematin, in the animal organism is a process 

 which remains absolutely unexplained. The question whether iron in an 

 inorganic or organic condition is assimilated in order to take part in the 

 synthesis, is far less interesting than that concerning the building material 

 of the hematoporphyrin. In order to make our position perfectly clear, 

 we will repeat again that we hold it to be perfectly possible that iron itself, 

 or in the form of salts, may be utilized as such for combining the two 

 hematoporphyrin molecules, i.e., in other words the iron is not necessarily 

 an organic constituent of hematin or of hematoporphyrin, and perhaps 

 it can take part in the synthesis only after it has been set free from any 

 organic compounds which may contain it. A glance at the above tentative 

 formula of hematin gives us some idea of the separate phases in its 

 construction. 



In the breaking down of chlorophyll, Schunck and Marchlewski l ran 

 across a derivative which they called phylloporphyrin. It has the fol- 

 lowing empirical formula, Ci6Hi 8 N 2 O. Hematoporphyrin corresponds to 

 the formula, CieHig^Os. According to this the two compounds differ 

 from one another in the amount of oxygen which they contain. March- 

 lewski 2 showed that both of these substances are to be regarded as dif- 

 ferent oxidation products of one and the same mother-substance, by 

 obtaining hemopyrrole, as well as the hematinic acids, from phyllopor- 

 phyrin. Thereby the close relationship between phylloporphyrin and 

 hematoporphyrin was established. 



Nencki and Zaleski 3 attempted to transform hematoporphyrin directly 

 into phylloporphyrin. They were able, however, to remove but one of 

 the hydroxyl groups from the hematoporphyrin. They obtained the 

 so-called mesoporphyrin which occupies an intermediate position between 



1 Ann. 278, 329 (1894); 284, 81 (1895); 288, 209 (1895); 290, 306 (1896). 



2 J. pr. Chem. 65, 161 (1902). 



3 Ber. 34, 997 (1901). 



