CARNOY'S CELL RESEARCHES. 487 
in general a very simple one: an equatorial furrow is formed, 
and deepens until the cell is divided. 
But the process is sometimes by no means so simple. In 
the cells of the Malpighian tubes of the larva of Aphrophora 
(*‘ Cytodiérése,’ p. 229, and fig. 7) it may be observed that the 
cytomitome, which in the static cell has an evident monocen- 
tric arrangement, its fibrils radiating regularly from the nucleus 
to the periphery, takes on a dicentric arrangement as soon as 
the nucleus has begun to be constricted. And in the fat-celis 
of Arthropods the matter is much more complicated and deeply 
interesting. Here the nucleus divides by simple 
constriction, without the accompaniment of the 
slightest karyokinetic phenomenon, but the cyto- 
plasm divides by means of a cell-plate. The plate 
(figs. 3 and 4) has the same constitution as a vegetal cell-plate. 
It is formed by the regularisation and thickening of the fibrils 
of the cytomitome. It makes its first appearance in the centre 
of the cell, and grows outwards towards the membrane. It 
may continue to grow out so till it meets the membrane, thus 
cutting the cell simply into two halves (fig. 4). Or it may 
delaminate, split at the edge into two flaps, which are reflected 
towards the poles, and grow outwards till they meet the mem- 
brane on two separate lines (fig. 3), thus dividing the cell, not 
simply into two halves, but into two spheroids, between 
which there remains a ring, of triangular section, of cytoplasm, 
that is not taken up into the bodies of the danghter-cells, but 
remains outside till it deliquesces and is reabsorbed. The 
plate is transformed into a permanent membrane in the usual 
way by fusion of its component granules. 
Carnoy has studied these cell-plates in Libellula, 
Acridium, Morimus, Bombus, Geotrupes, Eristalis, 
and Simulia. 
Indirect Cell Division.—Nucleus.—The first prophase of 
karyokinesis, marked by the passage of the chromatic filament 
into the loose skein form! (“lockere Knauelform, Spirem,” 
1T use the term “skem” for the “convolution” of Klein, as being 
shorter. ‘‘ Knaiuel” is, I think, best translated by. ‘“‘clew,” or “clue,” 
