ZOOLOGY AND BOTANY, MICROSCOPY, ETC. oy 



there arise separate dense spherical groups, becoming gradually denser 

 as the solvent evaporates, in consequence of which, when crystalliza- 

 tion commences, an empty space is formed in the interior of the 

 sphserocrystal. The sph^rocrystals of the Euphorbiaceae are organic 

 in their nature, and all belong to the inulin type. They occur in 

 especially large numbers in the coagulated latex of Euphorbia 

 spiendens, lieptagona, and erosa, in the last species with a diameter of 

 0" 8-1*0 mm.; also, less developed, in axial organs of the two first- 

 named species. The latter differ from other sphaerocrystals in 

 dissolving in glycerine after from four to eight weeks' immersion. 



2. Resin-crystals were found in the latex of all species of Euphor- 

 biacese examined, belonging to the cubical system. They are of three 

 kinds:; — viz. (1) forming angular dendritic groups; (2) groups 

 consisting evidently of closely packed separate crystals ; (3) those 

 which occur only isolated. 



3. Crystals consistingespecially of potassium and calcium malate. 

 These belong mostly to the rhombic and to the bi- and uniaxial 

 systems. True crystals of salts of malic acid also occur, to which he 

 gives the name of stellate crystals. 



Crystalloids in Trophoplasts, and Chromoplasts of Angio- 

 sperms.* — Pursuing his previous investigations of starch-generators 

 or trophoplasts,! A. Meyer has come to the conclusion that the 

 bodies described by Schmitz in algae under the name of pyrenoids | 

 are identical with the crystalloids of proteinaceous substances which 

 frequently occur in the fusiform trophoplasts of many flowering plants. 

 They differ from the protoplasm in having no framework or plastin. 

 The crystalloids of Phajus swell and dissolve with greater or less 

 readiness in water ; they are completely soluble in solution of chloral 

 hydrate ; when hardened by alcohol they are soluble in cold potash- 

 lye, but not when hardened by mercuric-chloride ; they are colourless, 

 homogeneous, and doubly refractive ; when hardened by picric acid 

 they are distinctly stained red by alum-carmine, but less easily 

 than the nucleus. In most of these characters they agree altogether 

 with Schmitz's pyrenoids. 



The autoplasts of foliage-leaves are usually formed as follows : — 

 The comparatively small trophoplast of a meristem-cell, which is at 

 first colourless and globular, or more or less regularly stretched by the 

 surrounding protoplasm, begins to grow slowly with the protoplasm 

 of its mother-cell. The framework or plastin thus increases in mass, 

 and grains of chlorophyll are formed within it, and possibly other at 

 present unknown substances soluble in alcohol. The mature auto- 

 plast appears to have changed its structure before it exhibits any 

 change in colour. The trophoplasts of the petals of angiosperms are 

 usually smaller than those of the foliage-leaves, but do not differ from 

 them in any essential respect. The trophoplasts of foliage-leaves 

 may be classed under the four following types : — (1) colourless 



* Bot. Ztg., xli. (1883) pp. 489-98, 505-14, 526-31. 

 t See this Journal, ii. (1882) p. 368. 

 J Ibid., iii. (1883) p. 405. 



