ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 269 



plant, combined with a substance which masks its colour. He de- 

 tails microchemical experiments which lead him to the conclusion 

 that the chlorophyll does not pre-exist in the cells, but that it may be 

 formed from the brown pigment-bodies by the action of a reducing 

 substance such as a volatile aldehyde, present in some cases in the 

 cells ; hence the occasional " greening " of the plant under special 

 circumstances. 



Occurrence of Calcium Oxalate in the Epidermal Cells of 

 Acanthaceae.*^ — Professor A. Weiss finds in the epidermis of the 

 organs of several species belonging to the Acanthaceaa a peculiar 

 deposit of calcium oxalate, not in any way connected with the cysto- 

 liths. Not only do these crystalline masses occur in the same cell 

 with starch-generators, starch, and chlorophyll, but the crystals are 

 of the two kinds, rhombic and klinorhombic, completely intermixed 

 with one another. 



Formation of Gum in Trees.f — Dr. W. Beyerinck, it will be 

 remembered,^ considered the formation of gum in trees to be due to 

 a pathological change brought about by the influence of a fungus. 

 Working independently, and in ignorance of Dr. Beyerinck's researches, 

 Dr. J. Wiesner has since arrived at a similar conclusion, except that 

 he attributes the formation of gum to the action of an unformed 

 ferment. This ferment he considers to belong to the starch-con- 

 verting or diastatic enzymes, but to differ from the ordinary members 

 of the group in that, while it converts starch into dextrin, it pro- 

 duces no sugar that reduces Trommer's solution. The seat of the 

 development of the gum-ferment appears to be the granular proto- 

 plasmic matter of the parenchyma-cells. From thence it attacks the 

 cellulose of the cell-walls, converting it into gum or mucilage, in the 

 latter case disappearing itself from the finished product. The ferment 

 probably converts any starch it may meet with into dextrin, though 

 never into a reducing sugar ; indeed it seems capable of arresting the 

 action of diastase in this direction, when added to a solution of 

 dextrin containing diastase. 



Wax of Box-leaves. § — Prof. G. A. Barbaglia has examined the 

 chemical constitution of the wax found chiefly on the upper sides of 

 the leaves of Buxiis sempervirens, and finds that, like Chinese wax and 

 bees'-wax, it contains palmitic acid. 



Stimulation of Gland-cells in Tentacles of Drosera dichotoma. \\ 

 — Mr. W. Grardiner finds that, as regards the general histology of the 

 tentacles of Drosera, the gland-cells of the head are provided with 

 delicate uncuticularized cell-walls, which are remarkably pitted on 

 their upper surfaces ; the other epidermal cells have their outer walls 

 excessively cuticularized and resistent, while their radial longitudinal 

 walls are freely pitted. In the typical resting gland-cell the proto- 



* SB. K. Akad, Wiss. Wien, xc. (1884) pp. 79-88 (1 pi.). 



t Bull. Torrey Bot. Club, xii. (1885) pp. 119-20. 



X See this Journal, iv. (1884) p. 419. 



§ Atti Soc. Toscana Sci. Nat., iv. (1885) pp. 115-6. 



II Proc. Roy. Soc, xxxis. (1885) pp. 229-84. 



