30 THE HISTOLOGICAL DISTRIBUTION [CH. 



pigment separates out either in crystalline or amorphous form. In 

 this solid state, anthocyanin may be pure, or may merely be absorbed 

 by substances in the cell, such as proteins, tannins. 



The following account is taken from Gertz (19) who has particularly 

 investigated this portion of the subject. Several cases of pigmented 

 cell-walls are recorded by Gertz among Monocotyledons, but no very 

 definite statements are made as to whether the colour is actually due 

 to anthocyanin. The cases quoted are in Pliormium lenax (Engelmann), 

 Eriophorum angustifolium (Wulft'), Sorghum (Kraus), Tillandsia dian- 

 toidea (Tassi), Pontederia crassipes (Hildebrand), Angraecum superbum 

 and Macroplectrum sesquipedale (Hering) ; Gertz also includes examples 

 which he has observed himself. Among Dicotyledons coloured cell- 

 walls are more rare. Red bast (Oxalis Ortgiesii) and red epidermis 

 (Epilobium montanum) are quoted ; in Jacquinia smaragdina ( Vesque 1 ) 

 the cuticle is crimson. According to Gertz, the coloured cell-walls 

 described in Homalomena rubrum (Nageli & Schwendener 2 ) and in 

 Geranium Robertianum, Begonia maculata, Quercus palustris, and Rumex 

 Acetosella (Wigand, 12) are artificially produced ; such artifacts can be 

 brought about by putting anthocyanin-containing cells in a medium 

 absorbing water, but in which anthocyanin is insoluble, such as ether. 

 The phenomenon can be demonstrated in leaves of Begonia spp. In 

 addition to the above cases, red pigment is found in walls of testa 

 cells in Abrus precatorius (Nageli & Schwendener 2 ) though Mobius (68) 

 found cell-sap too. Sclerotic cells of testa of Erythrina and Goodia 

 have blue, violet and red cell-walls (Tschirch 3 ) ; also in seeds of 

 Trifolium pratense (Preyer, 66). 



As regards the presence of solid and crystalline anthocyanin in 

 cells the following list of cases compiled by Gertz (19) is extremely 

 useful : 



Tillandsia ainoena, Hildebrand (30). 

 Aechmea sp., Dennert (14). 

 Allium Schoenoprasiim, Courchet (97). 

 Lilium Martagon, Overton (333). 

 Dracaena Jonghi, Hassack (393). 

 Convallaria majalis, Weiss (91). 

 Iris pumila, Dennert (14). 



1 Vesque, J., 'Memo-ire sur 1'anatomie cornparee de 1'ecorce,' Ann. sci. nat. (Bot.), 

 Paris, 1875, ser". 6, n, p. 82. 



2 Nageli, C. L., und Schwendener, S., Das Mikroskop, Theorie undAnwendung desselben. 

 Leipzig, 1877. 



3 Tschirch, A., Angewandte Pflanzenanatomie, Wien und Leipzig, 1889, Bd. i, pp. 62, 66. 



