ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
497 
Composition of Starch.* * * § — Herren C. Scheibler and H. Mittelmeier 
recur to the old view that starch is a mixture of two isomeric substances, 
granulose and starch-cellulose, of which the former constitutes by far 
the largest proportion, so that almost all the reactions assigned to starch 
are really those of granulose. It is easily transformed into soluble pro- 
ducts by acids and ferments, which is not the case with starch-cellulose. 
The carbohydrates may be classified in two principal groups, simple 
sugars and compound sugars, the latter, such as maltose, milk-sugar, 
and cane-sugar, being formed by combinations of the former with loss 
of water, according to the formula ti(C 6 H 12 0 6 ) — (n — 1)H 2 0. The 
so-called dextrin of commerce still contains sugar, from which it can be 
freed by precipitating three times by alcohol. Pure dextrin is still not 
an autonomous substance, but belongs to the class of carbohydrates which 
contain a free carbonyl. 
Starch-grains of Pellionia.t — Prof. A. Dodel has investigated the 
structure and Imode of development of the starch-grains in the stem 
of Pellionia Daveauana (Urticaceae), and states that they are formed 
exclusively by apposition. All the grains are first formed as small 
globes, either in the middle of globular or ovoid chloroplasts, or excen- 
trically in the latter, often in pairs or larger numbers beneath the 
periphery of the green protoplast. They gradually become ovoid, bean- 
shaped, or club-shaped, and grow entirely by apposition. The starch-gene- 
rators are regularly developed chlorophyll-grains of originally spherical 
or ovoid form. By the rapid growth of the contained starch-grain 
the chloroplast is burst, and the starch-generator is pushed aside in 
the form of a cap ; but the starch-grains are still enveloped by an ex- 
ceedingly thin layer of colourless protoplasm, and the green starch- 
generator frequently shifts its place on the surface of the latter during 
growth. The absorption of the starch-grains is effected by a diastatic 
ferment. 
Latex of the Fig.J — Sig. U. Mussi has investigated the composition 
of the latex of Ficus carica , and finds that it is composed of an enor- 
mous number of microscopic granules resembling in structure those 
of potato-starch, but containing neither starch, inulin, nor nitrogenous 
compounds. By filtration the latex may be divided into a liquid and a 
solid portion. The former contains vegetable albumin, traces of mineral 
salts, substances of a gummy and pectic nature, including a new diges- 
tive ferment cradin, glucose, and malic acid. The solid portion con- 
sists of cerotic acid, caoutchouc, a white substance insoluble in water, 
but soluble in cold alcohol, ether, and chloroform, and a substance 
occurring in thin scales, insoluble in water and in all ordinary 
solvents. 
Composition of Albuminoids.§ — M. H. Arnaud regards these sub- 
stances as composed of hydrocarbons, fatty substances, and urates, in 
varying proportions, on which depend their different reactions. They 
may be looked on as compound ammonium poly-cyanates, or as com- 
* Ber. Deutsch. Chem. Gesell., xxiii. pp. 3060 et seq. See Bot. Centralbl., 1891, 
Beih., p. 509. t Flora, lxxv. (1892) pp. 267-80 (2 pis.). 
f L’Orosi, xiv. pp. 297-304. See Journ. Chem. Soc., 1892, Abstr., p. 653. 
§ Comptes Kendus, cxii. (1891) pp. 148 51. 
1892. 2 m 
