IO8 BOTANICAL MICROTECHNIQUE. 



author gives no account of the mode of preparation of his 

 solutions, which were studied only as to their behavior with 

 caustic potash and sulphuric acid, and with the spectroscope, 

 it remains uncertain how far their different behavior is to be 

 attributed to foreign admixtures. 



I may remark here that secretions of pigment of a blue 



or violet color and of a granular 

 or crystalline structure have 

 been observed in various plants. 

 These consist most probably of 

 a compound of anthocyanin 

 with another substance not yet 

 recognized, perhaps a tannin. 

 FIO. 2 9 .-r e ii of the epidermis of a petal These secretions may be finely 



seen in the epidermis of the 



petals of various species of Delphinium. In the cell from 

 the epidermis of the petal of D. formosum, shown in Fig. 

 29, the beautifully blue secretions, which consist plainly of 

 delicate needles, lie in the violet cell-sap. But in this place 

 the pigment deposits may present the most various forms. 



ft. Anthochlorin. 



185. The yellow pigments dissolved in the cell-sap are 

 distinguished from xanthin, which occurs in the chromato- 

 phores, by never being colored blue by concentrated sul- 

 phuric acid, according to Courchet (I, 361-2). In other 

 respects, the yellow pigments contained in the cell-sap of 

 various plants show very different relations to chemical 

 reagents, as Courchet has shown. But our knowledge of 

 them is still too fragmentary to permit their classification. 



e. Coloring Matters wJiicli are first contained in the Cell-con- 

 tents, but later penetrate tJie Wall. 



186. According to Sanio (II, 202), Naegeli and Schwen- 

 dener (I, 501), and Prael (I, 67), all or nearly all the pig- 

 ments of the dye-woods belong in this category. This 

 follows with greater probability from the study of dried 



