ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 87 



of which the author again distinguishes two kinds, smaller with 

 sharper outline, and larger with less definite contour. 



The portion of the j)rotoplasm outside the nucleus may be classi- 

 fied under the following heads : — (1) Eeticulate lamellae and thicker 

 reticulate layers with larger and smaller meshes. (2) Chiefly round 

 the pale nuclei, especially those of epidermal cells, are pale, not 

 sharply defined, round or fusiform structures, such as pale strings and 

 threads, very commonly connected with the periphery of the nucleus, 

 and frequently again inclosing larger or smaller granules. (3) In 

 the epidermal cells are thinner or thicker layers of relatively coarse 

 refringent fibrillfe, sometimes interwoven, sometimes running parallel 

 to one another. (4) In some epidermal cells are also layers or flakes 

 of a pale finely granular or striated substance. 



Induction-currents act slowly on the refringent nuclei, very 

 rapidly on the pale, not homogeneous, nuclei, changing them into the 

 former kind. The chlorophyll-grains are also affected, with the 

 exception of the larger less sharply defined ones. Great changes are 

 also brought about in the protoplasm outside the nucleus. Alcohol 

 and chromic acid also cause certain changes, which should be borne 

 in mind when these agents are used as hardening materials. 



The author finally describes certain slow vermiform movements 

 which he observed in the protoj)lasmic threads and strings in the 

 tentacles of Drosera and in the stinging-hairs of Urtica, which are 

 somewhat more rapid in the threads which are separate or united 

 into wide-meshed nets. This motion consisted sometimes of oscilla- 

 tions with clearly distinguishable bondings in and out, sometimes of 

 a trembling motion, vi^ith scarcely jierceptible bendings. The dancing 

 motion of the granules he believes to be due to the same cause as the 

 oscillations of the threads, viz. rapid changes in the molecular frame- 

 work. 



Cystoliths of Cucurbitacese.* — 0. Penzig describes the cystoliths 

 which he has observed in the leaves and bracts of Momordica echinata 

 and M. cliarantia, while they are absent from the stem, tendrils, and 

 flower. In M. echinata they are found chiefly in greatly enlarged 

 epidermal cells in the under side of the leaf, fixed to a lateral wall ; 

 not, as in the corresponding cells of Ficus, to the outer wall. 

 Although the cystoliths are commonly found in adjoining cells 

 formed by division of a mother-cell, they do not unite. In M. 

 charantia numerous epidermal cells occur with cystoliths united into 

 groups, radiating from a common centre of the group. 



Chlorophyll.t — A. Hansen adopts the following method for 

 obtaining chlorophyll-green, using for preference young plants of 

 wheat. After boiling in water for half an hour, and drying, the 

 material is extracted in the dark with 96 per cent, alcohol, the extract 

 evaporated to one-eighth its volume, saponified with soda at the 

 boiling temperature, the ley diluted with water and treated with 

 sodium chloride. The green soap is then heated, first with petroleum- 

 ether, next with pure ether ; the former of which dissolves out the 



* Arch. Ital. Biol., iii. (1884) 1 pi. See Bot. Ztg., xlii. (1884) p. 334. 

 t Arbeit, Bot. Inst. Wiirzburg, iii. (1884) pp. 123-43. 



