144 Retrograde Varieties 



light for development, and that in the dark or in 

 a faint light the seedlings are apt to remain 

 green when they should become purple, but 

 aside from such consideration all organs always 

 come true to their color, whether pure green and 

 white, or whether these are combined with the 

 blue tinge. This constancy is so absolute that 

 the colors of the different organs convey the 

 suggestion, that they are only separate marks 

 of a single character. 



It is on this suggestion that we must work, as 

 it indicates the cause of the correlation. Once 

 present, the faculty of producing the anthocyan, 

 the color in question, will come into activity 

 wherever and whenever opportunity presents 

 itself. It is the cell-sap of the ordinary cell- 

 tissue or parenchyma, which is colored by the 

 anthocyan, and for this reason all organs pos- 

 sessing this tissue, may exhibit the color in ques- 

 tion. 



Thus the color is not a character belonging to 

 any single organ or cell, nor is it bound to a 

 morphologic unit ; it is a free, physiologic qual- 

 ity. It is not localized, but belongs to the en- 

 tire plant. If we wish to assume for its basis 

 material representative particles, these parti- 

 cles must be supposed to be diffused throughout 

 the whole body of the plant. 



This conception of a physiologic unit as the 



