ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 259 



ascertained of growing plants behind a screen of the solution. It 

 was found that the chromatophores tui-n green, and assimilate under 

 these circumstances, and that the red light is especially favourable to 

 the absorption and transport of starch. This clearly indicates the 

 purpose of the red pigment in the young shoots and other parts of tho 

 plant ; and the same is the explanation of the red colour of autumn 

 leaves. Different portions of a large leaf of Bicinus communis were 

 exposed to (1) light passed through ruby glass ; (2) light passed 

 through orange-coloured glass ; (3) light passed through an aqueous 

 solution of the red pigment of the red beet. After four hours : in 

 (1) the starch was found chiefly in the conducting tissue ; in the 

 palisade-cells there was not a trace of it. In (2) no important result 

 was found. In (3) the starch had transferred itself from the palisade- 

 tissue to the conducting mesophyll of the leaf. 



Crystals of calcium oxalate are very commonly found in the 

 palisade-cells and in the underlying mesophyll ; and these the author 

 believes to have an important function in connection with the trans- 

 formation of starch into other substances ; which, however, requires 

 further investigation. 



Coloured Roots and other coloured parts of Plants.* — F. Hil- 

 debrand describes the following parts of plants which are coloured 

 in an unusual manner. 



The roots of Pontederia crassipes, which hang down in the water, 

 are of a dark violet-blue colour, due, not to any pigment in the cell- 

 saj), but, like those of Fossombronia pusilla, to the cell-wall itself 

 being coloured. The under side of the floating leaves is provided, 

 which is very unusual, with stomata, the colour being also here in 

 the cell- wall of the guard- cells and adjoining epidermal cells. Hil- 

 debrand suggests that the purpose of this colouring may be to render 

 the parts in question less visible to animals. 



Wachendorfia thyrsiflora has bright red roots due to a coloured 

 fluid substance in the cells ; and presents the very remarkable 

 phenomenon of the pigment being formed even in absolute darkness. 



The bright red colour of the fruit of Bivina humilis is produced, 

 like that of the bracts of Euphorbia fidgens, by the superposition of cells 

 containing difierent pigments, orange and violet-red. 



In relation to the above paper, P. Ascherson f gives a description 

 of the instances known to him in which coloured roots occur in 

 plants belonging to the orders Pontederiacese, Hsemodoracese, and 

 CyperacejB. 



Starch in the Eoot.J — A. Tomaschek finds that the starch- 

 containing cells of the root are confined to the layer of meristem 

 between the root-cap and the body of the root, the remaining tissue 

 of the apex of the root not exhibiting a trace of starch. Shortly after 

 the first roots had emerged from the seed and taken a geotropic 

 direction, the starch had already disappeared from the apex of the 

 root, or was found in only a very few cells. 



* Ber. Deutsch. Bot. Gesell., i. (1883) ; Generalvers. in Freiburg, xxvii.-xxix. 



t Ibid., pp. 498-502. 



X Oesterr. Bot. Zeitschr., xxxiii. (1883) pp. 291-3. 



