1896.J Turacoporpliyrin to the Colouring Matter of the Blood. 341 



concentration. The identity of the spectrum of highly diluted solu- 

 tions of hsematin hydrochloride and of turacin is so complete that it 

 is impossible to distinguish from the photographs of the spectrum 

 which substance has been employed. 



Solutions of turacin in caustic soda or ammonia, so dilute as to be 

 almost colourless, and exhibiting, when a stratum 10 mm. thick is 

 examined, only the faintest shadow in the position of the stronger 

 of the two turacin bands in the green, exhibit an intense absorption 

 band which encroaches more and more on the ultra-violet as the 

 strength of the solution increases. With a solution just permitting 

 the recognition of both the turacin bands — the stratum examined 

 being 10 mm. — the band extends between In and M, the most intense 

 absorption occurring between h and L. The less refrangible border 

 of the band is sharply defined, whilst the more refrangible border 

 is less definite. As the solution is diluted, the band becomes narrower, 

 through less and less of the ultra-violet rays being absorbed. In 

 highly dilute solutions, the band, which is still intense, absorbs both 

 H and K. 



Turacin, therefore, like the acid compounds of haamatin, exhibits 

 an absorption band, which is exactly on the boundary of the ultra- 

 violet proper, and which extends further and further into the ultra- 

 violet, as the concentration of the solution increases. 



The identity of the spectrum of turacin with that of the hasmatin 

 compounds was so complete that it led me to surmise the existence of 

 a close relationship between the copper-containing body and the colour- 

 ing matter of the blood. Although I had ever since their publica- 

 tion been perfectly familiar with Professor Church's first researches, 

 his second investigation, of which the results were published in 1892,* 

 was unfortunately unknown to me. Without any knowledge of this 

 work, in making an oral preliminary communication of my first results 

 to the International Physiological Congress at Berne, in September, 

 1895, I expressed my conviction that turacin contains the same 

 atomic group which is the cause of the extreme violet and ultra- 

 violet absorption band in the spectrum of highly dilute solutions of 

 haemoglobin and its derivatives, and I predicted that by removing 

 the copper from turacin, I should be able to obtain a turaco-porphyrm 

 similar to the body which results from the removal of the iron from 

 hasmatin. It was only after I had performed the experiments 

 necessary for the elucidation of this point, and had obtained results 

 corroborating Professor Church's discovery of turacoporphyrin, that 

 the fact of his having anticipated me in this matter was brought 

 under my notice. 



The results of my special work ofi'er, however, an independent and 



* A. H. Church, " Researches on Turacin, an Animal Pigment containing 

 Copper," ' Phil. Trans.,' vol. 183 (1892), A, pp. 511—530. 



