THE RED BLOOD-CORPUSCLES 937 



Hamiatoporphyrin, C 34 H 38 6 N 4 . 

 Phylloporphyrin, C 34 H 38 O 2 N 4 . 



Phyllocyanin or phylloporphyrin, like the corresponding blood pigment, yields 

 hsemopyrrol on treatment with hydriodic acid and phosphonmm iodide. Thus 

 the same group forms the basis both of the substance which is responsible in the 

 plant for the assimilation of carbon from carbon dioxide, and of the pigment 

 which in the animal is the carrier of oxygen between the tissues and the surround- 

 ing medium. Nencki and Zaleski suggest that each molecule of hsematopor- 

 phyrin is built up out of four molecules of haemopyrrol, and give the following 

 as the possible structural formula of haemin : 



CH 3 .C C.CH : C (OH).C : C.CH : CH.C C.CH 3 



II II II II II 



HC CH O Fed HC CH 



NH 



\/ 

 NH 



CH 3 C C.CH : C (OH).C : C.CH : CH.C C.CH 3 



II II II II ' 



HC CH HC CH 



\/ \/ 



NH NH 



THE SYNTHESIS OF THE BLOOD-PIGMENTS. Chemists have not 

 yet succeeded in the artificial formation of haematoporphyrin, although 

 it is probable that the artificial formation of haemopyrrol will be 

 effected at no distant date. Given haematoporphyrin, however, 

 evidence has been brought forward both by Menzies and Laidlaw of 

 the possibility of forming artificially both haematin and haemoglobin, 

 or some substance indistinguishable from the latter. 



Reduced haemoglobin is a compound of haemochromogen and a 

 protein, globin. The splitting off of the prosthetic chromatogenic 

 group haemochromogen can be effected either by acid or alkali. 

 When the latter is employed we obtain a red solution which is fairly 

 stable, and can be converted by shaking up with air into ordinary 

 alkaline haematin. With acids the decomposition is easily carried 

 further. Even with 2 per cent, hydrochloric acid a certain amount of 

 haematoporphyrin is formed, and if the strength of the acid be increased 

 to 15 per cent, the whole of the iron is split off and the haemo- 

 chromogen is converted entirely into haematoporphyrin. 



If oxyhaemoglobin be treated in the same way it yields acid or 

 alkaline haematin directly, so that haematin must be regarded as 

 an oxyhaemochromogen. The distinction drawn by Hoppe-Seyler 

 between haemochromogen and reduced alkaline haematin had its chief 

 ground in the fact that pure haematin is not reduced to haemochromogen 

 by the action of such reducing agents as ammonium sulphide. The 

 conversion can, however, be easily effected by using a strong reducing 

 agent, such as hydrazine hydrate. Whether the haematin contains 

 the whole of the oxygen of the oxyhaemoglobin is doubtful. According 



