414 Mr Gustav Maun on the 



The fourth baud is also absent in benzolic extracts. I must 

 state, however, that I was not able to examine an extract 

 which contained chlorophyll in such a degree of concentra- 

 tion as to cause absorption similar to that shown in spectrum 

 3, and it is therefore possible that benzol would show an 

 absorption in the green part of the spectrum if a sufficiently 

 thick layer could be examined. Taking everything into 

 consideration, I am at present of the opinion that the fourth 

 band of Kraus is a decomposition-product, caused probably 

 by post-mortem changes ; whether it is possible, by the 

 addition of an alkali to the alcohol to counteract the ten- 

 dency of the chlorophyll to become acid, is doubtful. 



The centres of the two absorption-bands in the blue end 

 of the spectrum in living Spirogyra are about X 485 and 

 X 450. In an extract made with benzol the centres equal 

 X 486 and X 453 respectively, showing how closely a benzolic 

 extract resembles the normal spectrum ; an extract made 

 with xylol shifts the centres of the two bands slightly 

 towards the red end of the spectrum (X 492 and X 458 

 respectively) ; while an extract with petroleum ether shifts 

 the centres towards the blue end of the spectrum (X 479 

 and X 441 respectively). 



Whether the extract made with petroleum ether is identical 

 with Schunck's Chrysophyll in Ether 1 am not as yet pre- 

 pared to say ; but I must repeat that in very thick layers 

 not the slightest absorption was to be seen in the red end of 

 the spectrum. There seem to be, however, various kinds of 

 petroleum ether, for ether got from one dealer produced an 

 extract very like that of benzol, and with marked absorption 

 in the red end of the spectrum, while ether supplied by 

 another dealer gave an extract with a spectrum, as figured in 

 spectrum 10, Plate 11. One could detect that the two petroleum 

 ethers were not the same from the odour alone. 



Extracts made by triturating green tissues with benzol, 

 xylol, turpentine, petroleum ether, and similar bodies, have 

 one thing in common, namely, that they are of a yellow or 

 yellowish-green colour. If, now, an alcoholic extract of 

 chlorophyll, which is believed to contain normal chlorophyll, 

 is treated in such a way as to cause benzol, when brought in 

 contact with what is still considered to be normal chlorophyll, 

 to take up a blue colouring-matter, it is evident that some 



