of the Absorption Spectra of Chlorophyll, fyc. 395 



plate. Here the results of my experiments differ from those of 

 Tschirch, who found but one band in the zinc and copper compounds, 

 but the discrepancy may have arisen from the fact that he does 

 not state in his memoir what acid was in combination along with 

 the metal with phyllocyanin. That the zinc carbonate compound 

 of phyllocyanin should give two bands in the violet region corre- 

 sponding very nearly in position and relative intensity with the two 

 of phylloxanthin, and therefore, with the second and third violet 

 chlorophyll bands, is interesting from the fact that of all the 

 chlorophyll derivatives the spectrum of the phyllocyanin zinc car- 

 bonate in the visible region corresponds more closely than any of 

 the others with that of chlorophyll, and from the deductions arrived 

 at from this similarity by Schunck* as regards the functions of 

 chlorophyll as being a carrier of carbonic acid in the plant, just 

 as haemoglobin serves to convey oxygen in the animal economy. 



Alkachlorophyll, Phyllotaonin, Ethyl-phyllotaonin, Phylloporphyrin. 



In his " Contributions to the Chemistry of Chlorophyll " Schunck 

 has discovered that by the action of alkalis upon chlorophyll, the 

 above definite derivatives are produced in a crystalline forin.t 

 Alkachlorophyll, phyllotaonin, and ethyl-phyllotaonin all give the 

 single band in a pronounced and well- denned manner, corresponding 

 very nearly in position with the band in phyllocyanin, viz., at 

 about K/s, in phyllotaonin it being shifted slightly towards the 

 violet, and in the other two a trifle towards the red end of the 

 spectrum (Plate 5, figs. 6, 7, and 8). Alkachlorophyll also forms 

 a definite crystallised sodium salt. In an alcoholic solution the 

 band appears considerably shifted towards the red, but a watery 

 solution gives the band much obscured, in the same position as 

 the one in the alcoholic solution of alkachlorophyll itself (Plate 4, 

 figs. 9, 10, and 11). 



Phylloporphyrin on the other hand gives a double band, intense and 

 fairly well defined, the less refrangible one having its centre situated, 

 at the K|3 line (Plate 5, fig. 9). Phylloporphyrin forms a compound 

 with acids, which has a spectrum in the visible region quite 

 distinct from the very characteristic one of phylloporphyrin itself, 

 which consists of seven bands, while the acid compounds only 

 show three bands. J On examining the hydrochloric acid compound 

 in the violet region, a corresponding change is also found in the 

 spectrum, and instead of the double band, a single very intense 



* ' Annals of Botany,' vol. 3, pp. 65120. 



f 'Roy. Soc. Proc.,' vol. 39, p. 355; vol. 44, pp. 449454; vol. 50, pp. 

 312316 ; vol. 57, pp. 316319. 



J Schunck and Marchlewski, ' Koy. Soc. Proc./ vol. 57, p. 319. 



