ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 779 



growth frequently taking place by means of irregular prominences. 

 (4) Crystals exhibit a splitting both transverse and longitudinal. 



Sphaerocrystals.* — A. Hansen's extended paper on this subject is 

 now published. A preliminary notice of it was given ante, p. 416. 



Formation and Resorption of Cystoliths.t — Continuing his pre- 

 vious investigation of cystoliths, J. Chareyre has examined chiefly 

 those of Urtica Dodartii, U. pentandra, Cannabis sativa, Acanthus 

 mollis, A. lusitanicus, Tliunhergia alata, and Andrographis panieulata, 

 grown in different soils, in darkness and in light. He finds all the 

 seeds of UrticaceaB examined before germination to contain reserves 

 of food-materials composed entirely of aleurone-grains, in each of 

 which is a globoid ; and this is also the case with the seeds of 

 Acanthaceas, excejit those of Acanthus and of Hexacentris coccinea, 

 which have no cystoliths, and in which the reserve food-material 

 consists for the greater part of starch-grains. No portion of these 

 reserves contributes to the formation of deposits of calcium car- 

 bonate, whether as cystoliths or in any other form. Nor are they 

 employed in the formation of crystals of calcium oxalate, which 

 do not occur in the plants under examination during or in the 

 period following germination. When grown in pure silica the 

 cystoliths do not attain full development ; the pedicle is formed, but 

 does not develope cellulose at its apex, and always dies away when 

 entirely deprived of lime. Ordinary soil and soil formed of pure 

 calcium carbonate are about equally favourable to the formation of 

 cystoliths. When grown entirely in the dark, the seeds contain only 

 rudimentary cystoliths in which is no calcium carbonate. 



In reference to the influence of the death or etiolation of the leaf 

 on the quantity of lime contained in the cystoliths, the author found 

 that in the Acanthaceae etiolation, and even death, has no effect on 

 their formation. Among the Urticaceae, and especially Ficus elastica, 

 darkness causes, after from 10 to 15 days, complete disappearance 

 of calcium carbonate in the cystoliths, this disappearance being 

 connected chiefly with the cessation of the ftmction of the chloro- 

 phyll. The carbonate is not converted into bicarbonate ; and a 

 disappearance takes place of calcium oxalate as well as carbonate. 

 The lime has entered into combination with some other acid, which 

 is probably pectic acid ; it disappears from the leaves, and passes 

 into the stem, at least partially, in the form of calcium pectate. 



Development of Raphides.| — A. Poll has investigated the for- 

 mation of the raphides contained in the cellular tissue of the bulb of 

 Narcissus intermedium, where they are always accompanied by a strong 

 development of mucilage. They occur in longitudinal rows of cells, 

 and in older examples are always imbedded in mucilage resulting 

 from the deliquescence of the transverse walls, which mucilage escapes 



* Arbeit. Bot. Inst. Wurzburg, iii. (1884) pp. 92-122 (3 figs.), 

 t Bull. Soc. Bot. France, xxx. (1883) Seas. Extr., pp. viii.-xii. Cf. this 

 Journal, iii. (1883) p. 389. 



: Nuov. Gioru. Bot. Ital., xvi, (1884) pp. 56-9 (1 pi.). 



3 F 2 



