444 SCIENCE PROGRESS 



product the old name of chlorophyllan be retained. He finds, 

 using the acid fractionation method, that is probably a mixture 

 of a pure chlorophyllan proper, with more basic substances, of 

 probably a phyllocyanin, or phytochlorin type. 



He has also shown quite recently that phyllotaonin, on warm- 

 ing, is readily converted into another derivative, viz. allophyllo- 

 taonin, which is a weaker base than phyllotaonin, and can be 

 re-converted into this substance on treatment with weak alkali. 

 On treatment with alcoholic hydrochloric acid (20 per cent.) it 

 can be converted into substances of the phytorhodin type. 



The Chemical Relationship between Chlorophyll 

 and the Blood-pigments 



As already mentioned, Hoppe-Seyler noticed a similarity 

 between the product obtained by him by treating chlorophyllan 

 with caustic alkalis at high temperature, and the pigment pre- 

 viously obtained from haematin ; for this reason he gave to the 

 product the name of phylloporphyrin to denote its apparent 

 relationship to the blood-pigment haematoporphyrin. 



Subsequently, Schunck and Marchlewski succeeded in prepar- 

 ing phylloporphyrin in a condition of much greater purity than 

 it had hitherto been obtained, and made a comparison between 

 its absorption spectrum and that of haematoporphyrin. They 

 noticed an astonishing similarity, which demonstrated beyond 

 doubt the intimate chemical relationship between the two 

 bodies. 



In the meantime, haematin and its derivative haematoporphyrin 

 had formed the subject of very careful investigation by Kiister 

 on the one hand, and by Nencki and Zaleski on the other. It 

 was found as the result of their investigations that haemato- 

 porphyrin and phylloporphyrin differed from one another only 

 in their oxygen content. Adopting the formulae most in accord- 

 ance with the careful analyses of Zaleski, the two substances can 

 be best represented by the following formulae : 



Haematoporphyrin . . . C3 4 H 3S 6 N 4 . 

 Phylloporphyrin .... C 3 4H3 8 2 N4. 



Nencki and Zaleski then attempted to convert the one body 

 into the other by reduction of haematoporphyrin with hydriodic 

 acid of phosphorus. Instead of obtaining phylloporphyrin, they 

 produced an intermediate substance, which yielded a crystalline 

 hydrochloride, and which had a chemical composition inter- 



