BOTANICAL GAZETTE. 6g 



detached from the living protoplasm of an organism, and no effect of 

 any kind can be produced upon COjby its agency when thus isolated. 



It may be urged that the chlorophyll when extracted from the 

 chlorophyll-grain is chemically altered by the solvent (alcohol or ether) 

 used. But the solution obtained by appropriate treatment of green 

 leaves gives precisely the same absorption-bands as does the green 

 substance in the plant (the whole series being moved a very little to 

 the blue end according to the known law that absorption bands travel 

 in that direction when a less dense solvent is substituted for a more dense 

 one). 



It cannot, however, be stated that a negative has been directly 

 proved with regard to the supposed CO.-decomposing property of 

 chlorophyll. It is possible that chlorophyll when extracted by sol- 

 vents from the chlorophyll corpuscles may yet be shown to possess 

 that property. The solvents themselves may. so long as they are pres- 

 ent, exert an inhibitory effect. Whilst ether and alcohol may do so, 

 it IS possible that vegetable fats may be more propitious, or that some 

 other solvents may be found more closely resembling the natural sol- 

 vent or the chlorophyll-corpuscle than those at present known. 



Apart from the absence of sufficient evidence to warrant the as- 

 sumption that chlorophyll has a specific chemical action on carbonic 

 acid in the presence of sunlight, three facts render the supposition 

 improbable : 



I. If chlorophyll were the active agent in C0.^-decomi)osition, 

 we should expect the rays absorbed by chlorophyll to be those most 

 efficient in promoting such decomposition. Such, it has been shown 

 by Sachs and others, is not the case. 



2 It may well be that chlorophyll has other work to do in its re- 

 lation to the specific chemical activities promoted in protoplasm by 

 the incidence of the luminous rays. Prof. Pringsheim suggests that 

 the true function of chlorophyll is by its general absorbent action 

 on light to protect the protoplasm of the cell from excessive oxidation, 

 and especially to protect that of the chlorophyll corpuscles. Oxida- 

 tion being thus nearly or entirely arrested in these corpuscles, whilst 

 proceeding in a lessened degree in the general protoplasm of the cell, 

 the protoplasm of the chloroj^hyll corpuscles is at liberty under the influ- 

 ence of those rays of tight which arc allowed to pass by the chlorophyll (the 

 very reverse of former suppositions on the subject) to decompose 

 COj and synthesize the elements of starch (or of hypochlorin). 



3. That so special an activity as the decomposition of CO2 and 

 the synthesis of the elements of starch is due to protoplasm and not 

 to the chemically simple (comparatively) chlorophyll is probable on 

 ^z/r/m grounds. 



If this green pigment is really something more than a screen for 

 protoplasm, its character must be established by direct demonstration 

 of its capabilities. The facts, as at present in evidence, look very 

 much as though chlorophyll had been assigned a position of unmer- 

 ited dignity.— E. Ray Lankester, F.R.S. in Nature, April 15. 



Some Big Trees of Indiana. — In Case's Botanical Index for 



