120 CHLOROPHYLLINE CHEOMULES. 



Conclusion. 



In order to define more accurately my views concerning these 

 chlorophylline chromules, I will now compare the distinguishing 

 characteristics of th^ various groups, and add a few remarks on 

 the diverging views of other physiologists. 



In the coui'se of his recapitulation the author, after allading to the 

 varying degrees of solubility in alcohol and in water, presented by the 

 anthoxanthine group, remarks that in addition to these we very 

 generally meet with other yellow chromules ofcen associated with the 

 cell-walls of plants which do not even possess the three chlorophyll 

 bands in the blue, but in their place an absorption beginning from the 

 violet end and spreading continuously over the spectrum. This 

 absorption might possibly be conceived as an intensification of the 

 chlorophyll band VII., in which case these chromules would have to 

 be regarded as the last members in the chlorophylline series. 



It must now appear evident why I could not agree with Fremy, 

 rilhol, or Kraus in their descriptions of the green and yellow 

 chromules, and still less with Sorby respecting the several chromules 

 which he alleges to have obtained from various plants, and which he 

 reo-ards as distinct and undecomposed substances pre-existing in the 

 plants and capable of definite analysis. 



It is certain that many of these chromules must have been 

 deprived of their original spectrum characteristics by the treatment to 

 which they were subjected. In the determination of the spectra, 

 moreover, the influence of the solvents, that of concentration, and of 

 the thickness of layers, seem to have been equally disregarded. It is 

 clear that a single spectrum can give us no adequate information as to 

 the absorption phenomena of any chromule, unless we are acquainted 

 beforehand with its phases of absorption, and know to which phase of 

 the bands it corresponds. Sorby has nowhere stated with reference 

 to his yellow chromules, to which he ascribes two separate bands in 

 the blue, to what extent the various positions of the bands are 

 influenced by the solvents, nor how they depend on the thickness of 

 the layers ; nor does he state, that with an increase of the chromule 

 additional bands do not appear. I doubt not that the whole, perhaps, 

 of his yellow chromules — one only excepted — would suddenly reveal 

 also the chlorophyll bands of the first half, if my method were 

 applied. 



If in future more accurate distinctions are attempted to be drawn, 

 it will be necessary in every case to demonstrate carefully to what 

 extent the observed difference in the spectra might or might not be 

 explained by the solvents employed, or whether they do not depend 

 on some cellular contents of the plants examined; and finally, it 

 would have to be shown that they are more than particular phases of 

 the same absorption bands. 



[Abstract of paper in the " Monatsbericht " of the Royal 

 Academy of Berlin, October, 1874.] 



