of t lie Absorption Spectra of Chlorophyll ', $r. 393 



E and F. According to the investigations of Schunck and March - 

 lewski,* these changes may be explained by the supposition that 

 phylloxanthin is formed in the first case, and phyllocyanin in the 

 second. These changes take place in a greater or less degree in 

 every chlorophyll solution on standing, according to the amount an.d 

 strength of acid present originally. 



I have fonnd in all the various chlorophyll solutions I have 

 examined, even in those which from the commencement gave the 

 fourth band darker than the third, and those in which the same 

 change had taken place on standing, that no change had taken place 

 in the violet, the only change being that more and more of the 

 ultra-violet rays are absorbed. In the purest solution the total 

 obscuration started at the line N, while in others the total obscura- 

 tion commenced at the line H 2 . But in the case of a solution which 

 had been exposed to the action of direct sunlight and which showed 

 the fifth band, then the bands in the violet had disappeared alto- 

 gether, leaving only a general absorption in the ultra-violet. As 

 will be seen from Plate 5 (figs. 2 and 3), the second and third of 

 these violet bands are identical in position with the two bands found 

 in phylloxanthin, while the first corresponds in position to a new 

 sixth band I have found to exist in the spectrum of phyllocyanin 

 when the solution is examined in a more concentrated form than 

 usual, and which appears distinct but faint when photographed. 



The chrysophyll was obtained by Schunck's methodf and 

 examined in an alcoholic solution ; the carotin crystals were 

 obtained from the carrot root by the process of Arnaud, and was 

 likewise examined in an alcoholic solution. In each three very 

 distinct characteristic bands were found, which agrees with the 

 statement of Tscliirch, but the bands from my photographs are not 

 in identical positions, those in the carotin being slightly shifted 

 towards the violet end. 



Like Tschirch, I find that both these derivatives are very trans- 

 parent to the ultra-violet rays. From Plate 3 (figs. 2 and 3) it will be 

 seen that the three chrysophyll bands occupy intermediate positions 

 compared to the three chlorophyll bands, which seems to point to the 

 supposition that chrysophyll does not exist in chlorophyll solutions 

 as such, but under certain conditions only is formed by decomposi- 

 tion of a derivative,^ and then crystallises out, or that if it does 

 exist in the solutions it must be in a very small quantity, otherwise 

 the bands would overlap each other, and the result would be a total 

 obscuration, which I have only found to be the case in a chlorophyll 

 solution exposed to the action of direct sunlight. 



* ' Boy. Soc. Proc.,' vol. 57, p. 321. 

 f ' Koy. Soc. Proc.,' vol. 44, p. 449. 

 % Hansen, ' Die Farbstoffe des Chlorophylls,' 1889, p. 58. 



