ry 



Kraemer: Color in plants 91 



usually in largest amount at the termini of the branches, as in 

 flowers and terminal leaves, or in roots, or in both tops and roots. 

 Their occurrence in those portions of the plant which are young 

 and growing, points to the conclusion that they are not to be disre- 

 garded in the study of metabolic processes. Goebel likewise 

 holds to this view. He says that it is " vi 

 feature of color which so often appears when the propagative or- 

 gans are being brought forth has some connection with definite 

 metabolic processes, although up till now we cannot recognize 

 what these are." 



5. The distribution of the so-called flower color-substances in 

 other parts of the plant than the flower also points to the same 

 conclusion, and that the part which they play in attracting insects 

 to flowers is incidental rather than fundamental. (The fact that 

 certain colored flowers as in spruce are pollinated by the wind, 

 would tend to confirm this view.) 



6. The occurrence of chromoplastids in a reserve organ, as in 

 the tuberous root of carrot, and the similar occurrence of chromo- 

 plastids and of reserve starch in the petals of the buttercup, lead 

 to the inference that the petal of the buttercup, like the root of the 

 carrot, has the function of storing nutrient material. In each case 

 cells containing chromoplastids rich in nitrogenous substances are 

 associated with cells containing reserve materials. 



7. The feeding of plants with chemicals or color-control solu- 

 tions has not so far, in my hands, produced any marked changes 

 in the colors of the flowers, only some slight effects being noted 

 which might be attributed to other causes. Knowing that plants 

 have a certain individuality and certain inherent qualities or ten- 

 dencies, one could hardly expect other than negative results. On 

 the other hand we know that the plant is a rather plastic organism, 

 and for this reason we are more or less justified in carrying on ex- 

 periments along the line indicated. 



The fact that of thousands of dyes or color-substances only a 

 few are taken up by the plant and carried as high as the flower, 

 would tend to the probability that only certain chemicals or sub- 

 stances would be taken up and thus exert an influence upon the 

 coloring matter in the flower. If such profound changes arise in 

 plants as are provided by the mutation theory, is it too much to 



