vi] INFLUENCING THE FORMATION OF ANTHOCYANINS 99 



a powerful agent in assisting the formation. Cultures in distilled water, 

 both in the light and in the dark, produced no anthocyanin. To obtain 

 absolutely comparable results, parts of the same leaf, A, B, C and D 

 were treated as follows. A and B were placed in 5 % sugar solution, 

 C and D in distilled water ; A and C were exposed to the light, B and 

 D kept in the dark. The results were as before. Both A and B formed 

 anthocyanin, but it was insignificant in B; C and D were free from 

 anthocyanin. 



Tradescantia Loekensis. Again the leaves are variegated red, 

 white and green. No chlorophyll occurs in the white parts except in 

 the guard cells. In cane sugar the result was negative and no antho- 

 cyanin was formed. Gertz has no suggestions to offer except that 

 possibly some unknown factor is essential to the formation of pigment. 



Beta vulgaris. Only negative results were obtained. 



Rumex domesticus. A variegated green and white form was used, 

 of which the white parts, including the guard cells of the stomata, 

 are entirely free from chlorophyll. In less than one day in 5 % sugar 

 solution, anthocyanin appeared, and was found to be located in the 

 lower as well as in the upper epidermis. In the dark, less pigment was 

 formed. Experiments were made with ordinary Rumex, and were in 

 complete agreement, since anthocyanin was formed chiefly in the 

 epidermis (except stomata). Similar observations on R. Patentia have 

 also been made by Palladin (203), 



Cornus florida. The leaves have green and white parts, the latter 

 being free from chlorophyll. After a week in 10 % cane sugar they 

 showed only traces of anthocyanin which was located in the spongy 

 parenchyma. 



Euonymus radicans. In 10 % sugar, the albino parts showed a 

 faint reddening in the lower epidermis with the exception of the stomata. 



Lonicera brackypoda. The leaves have white reticulations on a 

 green ground. After a week in 10 % cane sugar solution, anthocyanin 

 was found in the palisade parenchyma. 



Other experiments were made with green leaves as follows : 



Plantago major. In 10 % sugar solution, the pieces of leaves red- 

 dened strongly, and anthocyanin was located entirely in the lower 

 epidermis except the stomata. Attempts were made to induce antho- 

 cyanin formation in sugar cultures in isolated epidermal layers, but they 

 were unsuccessful. 



Sium latifolium. In 10 % sugar solution, anthocyanin appeared 

 readily in pieces of leaves, as well as in entire leaves and shoots, and 



72 



