THE RED BLOOD-CORPUSCLES 937 



HaBmatoporphyrin, C 34 H 38 O 6 N 4 . 

 Phylloporphyrin, C 3 4H 38 2 N 4 . 



Phyllocyanin or phylloporphyrin, like the corresponding blood pigment, yields 

 haemopyrrol on treatment with hydriodic acid and phosphonium 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 hsernatopor- 

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

 as the possible structural formula of hsemin : 



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



II II I 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 hsernatoporphyrin, although 

 it is probable that the artificial formation of hsernopyrrol will be 

 effected at no distant date. Given hsernatoporphyrin, however, 

 evidence has been brought forward both by Menzies and Laidlaw of 

 the possibility of forming artificially both haeniatin and haemoglobin, 

 or some substance indistinguishable from the latter. 



Reduced haemoglobin is a compound of hseniochromogen and a 

 protein, globin. The splitting off of the prosthetic chromatogenic 

 group hsemochrornogen 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 

 hgematoporphyi'in 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 haemochrornogen and reduced alkaline haematin had its chief 

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

 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 



