116 CHLOROPHTLLINE CHR0MULE9. 



two substances, viz., a yellow one without absorption in the first half 

 of the spectrum being present in larger quantity, and the normal 

 green chlorophyll in a less degree, according to which view chloro- 

 phyll would be produced without the agency of light. There are no 

 facts to support this theory, however, and it seems much more probable 

 that etiolin is an unmixed substance, being a yellow modification of 

 chlorophyll. For we have never been able to separate etiolin into 

 green and yellow components, as in the case of chlorophyll. 



According to this view, therefore, concerning the relation between 

 etiolin and chlorophyll the proposition respecting the influence of 

 light requires qualifying, by saying that while the formation of chlo- 

 rophyll in general is independent of light, it is a yellow form of 

 chlorophyll that is produced in the dark, but a green modification in 

 the light. 



II. The cliromule of yelloiv blossoms. 



The changes in colour which the parts of yellow blossoms and 

 fruits undergo during their development, point to a close connection 

 with the chromule of chlorophyll. 



Its optical properties difi'er only in having weaker absorptions in 

 the first part of the spectrum. Kraus seems to have been the only 

 one who has subjected the chromules of yellow blossoms to spectrum 

 analysis. From not using layers sufficiently rich in chromule he failed 

 to detect the chlorophyll bands of the first half of the spectrum, just 

 as he had done in the case of etiolin. 



This weakening of some of the chlorophyll characteristics varies 

 in different flowers. The strength of the bands, however, seems to 

 remain constant in plants of the same Natural Order. In some of the 

 examples which showed the weakest absorptive power, such as a kind 

 of yellow Rose, Carthamnus tinctorius, and various yellow Dahlias, 

 even with concentrated layers 370mm. in thickness, there was scarcely 

 a trace of band I. to be seen. The yellow chromules of blossoms ac- 

 cordingly form a continuous series of gradations of chlorophyll. Even 

 those which difter most betray their genetic connection by presenting 

 similar absorption bands in the blue. 



In this anthoxanthine series the red fluorescence is more or less 

 apparent in proportion to the strength of thechlorophylline absorption 

 phenomena. 



There is a further important fact, viz., that in proportion as the 

 peculiar optical characteristics of chlorophyll vanish, the solubility 

 of the Anthoxanthin in water increases. This fact obviously throws 

 light on the nature and origin of the yellow chromules soluble in 

 water which occur associated with chlorophyll in the green parts of 

 plants and which finally lose even the last spectrum marks of chloro- 

 phyll- 



Special precautions were taken to select for anthoxanthine exami- 

 nations examples entirely free from any accidental admixture of green 

 chlorophylline particles. The optical qualities of anthoxanthin can- 

 not be infeiTed from the forms of these particles. They most fre- 

 quently occur as very minute, round or oval, elongated, pointed, or 

 spindle-shaped corpuscules ; sometimes solid and sometimes hollow. 

 Frequently it pervades a protoplasm entirely amorphous, and in rarer 



