144 P- Q- KEEGAN [fkbhuary 



merely modifications of only one fundamental substance. Tainted with 

 German alchemical mysticism, Schubler and Frank, A. P. De Candolle, 

 and Marquart successively sought for and insisted on the close con- 

 nection and genetic relationship of the reds, blues, and yellows : they 

 went further, they proclaimed that the colours of flowers were all 

 derived from and indissolubly bound to chlorophyll. 



Now, it is obvious that no thorough and complete scientific under- 

 standing of this subject could possibly be attained so long as this sort 

 of poetically " evolutional " imagination held the field. How eminently, 

 then, does it stand to the credit of those acute and able chemists, 

 Fremy and Cloez, Martens and Filhol, that they were not moved or 

 deterred in the slightest degree by the a priori postulates of their 

 German predecessors, that, in fact, they entirely ignored the connection 

 of these brilliant colours with chlorophyll. No doubt Filhol declared 

 that " there is the most direct analogy between xanthine and chloro- 

 phyll," but he never sought to derive the one from the other. He 

 and his collaborateurs examined the floral pigments in and by them- 

 selves, they were never troubled with evolutionary imaginations and 

 hypotheses, and hence they led the way to discoveries which fitly 

 served as bases and props for farther research and enlightenment. 

 Berzelius had little doubt that pure chlorophyll may be the origin of 

 the yellow and red colouring matters of autumn leaves, but he admits 

 that he was never able to reproduce chlorophyll by means of xantho- 

 phyll, nor transform chloroj^hyll into xanthophyll. Mohl, in 1837, 

 would not admit that chlorophyll has any relation with the red colour 

 of autumn leaves, but he does not deny its intervention, though only 

 indirectly, in the red colour of fruits ; there is nothing to show, how- 

 ever, that he considered that there was any chemical connection 

 between these bodies. In 1850 Morot, in criticising Marquart's views, 

 observes that " chlorophyll is not found in the most superficial layers 

 of cells where the blue, violet, and red colouring principles are chiefly 

 found ; in the more deeply situated cells of the mesophyll there exists 

 much chlorophyll, and at a certain epoch the red substance is seen to 

 take birth there, but at the same time the chlorophyll persists, and 

 this red substance seems to proceed from cell sap, which is colourless 

 beforehand ; this sap by the prolonged action of a weak acid becomes 

 red without passing by blue." This passage seem to me to be the 

 very first distinct and definite declaration on chemical grounds, partly 

 at least, that the green matters of leaves are not connected with the 

 red and blue matters, although, as Morot admits, it may be affirmed 

 that chlorophyll, anthocyan, and the red matter may be modifications 

 of one and the same substance ; but it is hardly necessary to rejoin 

 that this is totally different from the affirmation that the blue pigment 

 is a direct derivative by dehydration of chlorophyll itself, as Marquart 

 maintained. 



In 1858 Morren published his famous " Dissertation sur les feuilles. 



