INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 685 



chloroform in tlie same way as before. Usually this second washing 

 suffices to remove all that remains of the green colouring princii)lc. 

 If the supernatant portion is turbid its transparency will be restored 

 by pouring into it a small quantity of 90 per cent, alcohol. We then 

 have the two colouring principles separately, and it suffices to 

 evaporate the solutions to obtain the principles in a solid state. 



Green Colouring Matter — Chlorophyll. — The solution of the green 

 colouring matter possesses a fluorescence of a wine-red colour ; by 

 transmitted light it has an emerald green tint, but this tint may bo 

 more or less deep. The properties of this colouring matter show 

 a very great analogy with those of chlorophyll. Its spectrum 

 (Fig. 54, No. 3) is altogether similar to that of chlorophyll (No. 1) ; 

 the band III. above is less marked. We may therefore conclude 

 with Kraus and Millardet {loc. cit.) that the green colouring matter 

 extracted from diatomine, either by benzine or by chloroform, is no 

 other than the chlorophyll of the higher plants. 



A proof of this opinion may be found by collecting the gas which 

 escapes during the respiration of diatoms exposed to the light. It is 

 easy to prove that this gas is oxygen, which evidently arises from 

 the decomposition of the carbonic acid by the chlorophyll under the 

 action of light. 



Yellow Colouring Matter Phi/coxanthine. — The alcoholic solution of 

 yellow colouring matter has a brick-red fluorescence, less intense 

 than that of diatomine. By transmitted light it shows a fine golden 

 yellow tint, which disappears after a short time even in di ft used 

 light. If this solution is diluted with twice its bulk of distilled 

 water it neither precipitates nor becomes turbid. 



Concentrated sulphuric and hydrochloric acids communicate to 

 this solution a greenish-blue tint, exactly similar to that of certain 

 Oscillatorieaj. 



If we examine by the sjiectroscope a solution of yellow colouring 

 principle, concentrated and completely freed from chlorophyll, wo 

 find (Fig. 54, No. 2) a very black band in the red from 108 to 

 113, and the second part of the spectrum is absorbed as far as the 

 middle of the green at 65, decreasing as far as 70. The band I. is 

 displaced towards the extremity of the red, and docs not agree with 

 that of chlorophyll. 



All the physical and optical properties just cited show that 

 there exists a great analogy between the phycoxanthine of Kraus 

 and Millardet and the yellow colouring matter of diatomine ; there- 

 fore I do not hesitate to consider them identical, as do these two 

 authors.* 



Kraus a)ul Millardet have proved the scarcely perceptible presence 

 of band II. in the spectrum ot i)hycoxiinthiiio ; the cau.sc of tliis result 

 must be attributed to the process ciui)loyed by these two observei"S, 

 the benzine not succeeding in eliminating the last truces of chh)ro- 

 phyll. 



M. Nebelung,t in using the same process to scjiarato the two 

 colouring princijiles, was also able to sco with groat difficulty band II. 

 * Loc. (it., \). 'S2. t l'"*"- •"'• . p •'"••'^- 



