100 PHYSIOLOGICAL CONDITIONS AND FACTORS [CH. 



was found to be localised in cells of the mesophyll. With Cerefolium 

 sylvestre negative results were obtained. 



Epilobium parviflorum. In 5 % sugar solution, anthocyanin 

 developed plentifully in the lower epidermis and occasionally in the 

 upper. 



Euphorbia Cyparissias. In bracts in 10 % sugar solution, antho- 

 cyanin was formed in both the upper and lower epidermis. In Phyto- 

 lacca decandra it appeared in the epidermis (except stomata). 



Thus Overtoil's view, which is expressed as follows "...mit 

 Ausnahme der untergetauchten Wasserpflanzen scheinen solche Versuche 

 fast durchweg bei denjenigen Pflanzen negativ auszuf alien, deren 

 natiirliche Rothfarbung...der Gegenwart von rothem Zellsaft in den 

 Epidermiszellen zu verdanken 1st," is, as Gertz points out, not correct; 

 for colour due to anthocyanin appears entirely in the epidermis in 

 Oplismenus imbecillis, Euonymus radicans, Plantago major, Euphorbia 

 Cyparissias and Phytolacca decandra; both in the epidermis and meso- 

 phyll in Rumex domesticus, Tussilago Farfara and Epilobium parviflorum. 

 On the other hand in Cornus florida, Lonicera brachypoda and Sium 

 latifolium it appears in the ground parenchyma. These results are 

 also in accordance with those of Katie. 



Thus it would appear to be definitely settled that chloroplastids 

 are not essential to anthocyanin formation from the results with leaves 

 of Oplismenus imbecillis , Rumex domesticus, Cornus florida, Euonymus 

 radicans and Lonicera brachypoda, though the results with Tradescantia 

 and Beta are negative. Yet Gertz does not .seem to be quite assured 

 on the point, partly because, as he points out, the epidermal leucoplastids 

 are closely related to chloroplastids, and partly because the epidermis 

 is connected with chloroplast-containing cells. 



As regards the effect of light on the results of sugar-feeding, Overton 

 maintained that colour was not produced in the dark. This was not 

 found by Gertz to be the case with Oplismenus and Rumex, and Katie, 

 moreover, demonstrated that Hydrilla, Hydrocliaris, Allium and Pha- 

 laris develop pigment in sugar cultures in the dark. Gertz is of 

 the opinion that under natural conditions the appearance of antho- 

 cyanin may not be very largely affected by illumination, as a whole 

 constellation of factors may take part in its formation in the kind of 

 way we have tried to indicate in the previous sections. 



Gertz finallv considers the formation of anthocyanin in petals 

 resulting from sugar-feeding. As we have seen, Overton failed to get 

 any result with Pelargonium and Anemone. Gertz considers that such 



