204 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
numerous in the female nuclei ; there is also a difference in the structure 
of their framework. 
Elementary Structure of the Cell. — Replying to an objection of 
Pfeffer’s, Dr. J. Wiesner * states that, according to his view, the plasomes 
of one and the same cell resemble one another only in their main features 
— such as divisibility, growth, assimilation — but that they differ from 
one another in specific properties. 
Cell-division following Fragmentation of the Nucleus.! — Sig. L. 
Buscalioni describes the phenomena which take place in the portion of 
the endosperm which lies between the cotyledons in seeds of Vicia 
Faba. Karyokinetic is gradually replaced by direct division, during 
which the formation of membrane still takes place, so that an ordinary 
tissue is formed with a nucleus in each cell. New septa continue to be 
formed, until at length each nucleus is divided into a number of new 
ones, and a corresponding number of new cells are formed. This is 
accompanied by a change in the mode of cell-formation, of the nature of 
encysting. At certain spots in the endosperm, dark nucleated masses 
of protoplasm make their appearance, of irregular form, and often con- 
nected with one another by delicate threads. These are at first naked, 
but become enclosed in a membrane of cellulose which is at first very 
delicate, but becomes gradually thicker. The same membrane will 
sometimes enclose a number of nuclei. 
Callose in Phanerogams.^ — M. L. Mangin recapitulates the micro- 
chemical tests by which the presence of callose can be detected, viz. : — 
It is colourless, amorphous, insoluble in water, alcohol, and Schweizer’s 
reagent, even after the action of acids, very soluble in cold caustic 
potash and soda, soluble in the cold in sulphuric acid, calcium chloride, 
and concentrated stannic bichloride, insoluble in the cold in the alkaline 
carbonates and ammonia, which cause it to swell, giving it a gelatinous 
consistence. It is more abundant in Algae and Fungi than in Vascular 
Cryptogams or Phanerogams, though it occurs frequently in these. It 
is sometimes formed during the development of the tissues, and plays 
an important part in the dissociation of tissues and the perforation of 
membranes. Thus in sieve-tubes it forms, during the period of repose, 
a cushion which obliterates the sieve-pores, and which disappears when 
growth becomes again active. It also often remains unchanged in 
permanent organs till the death of the plant, as in epidermal cells, 
cystoliths, hairs of the Borragineae, &c. The tissues in which callose 
is formed are specially described in the cases of the vine, Myosotis 
palustris, and Geranium molle. 
Cellulose and its Forms. § — Herr W. Hoffmeister discusses the 
various modes of preparing pure cellulose and cellulose-gums. He con- 
siders it probable that even true cellulose (hydrate of dextrose) is not 
an independent substance, and that the same is true of cellulose-gum. 
* Bot. Ztg., 1. (1892) pp. 473-6. 
t Giorn. K. Accad. Medicina, April 22, 1892. See Bot. Centralbl., li. (1892) 
p. 332. . 
X Bull. Soc. Bot. France, xxxix. (1892) pp. 260-7. Cf. this Journal, 1890, 
p. 734. 
§ Landwirthsch. Versuchsstat., xxxix. pp. 461-70. See Bot. Centralbl., 1892, 
Beih., p. 429. 
