ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
715 
As to the cause of the initial longitudinal splitting of the chromo- 
somata, this cannot be referred to a mechanical pull exercised by the 
spindle-fibres. It may be, as Boveri thinks, an independent vital 
process, a reproduction of chromatin elements ; or it may have some 
relation to the formation of the intranuclear portion of the spindle- 
fibres. The unravelling of linin-threads from the chromatin of the 
nucleus may give some stimulus to the biserial arrangement of the 
chromatin elements which remain. 
The “Intermediate Body” in Cell-division.* — Herr B. Solger 
has studied the division of the connective-tissue cells in the amnion of 
the rat, and has observed within the bridge between two almost separated 
cells a rod-like body which stains more darkly than the cell-substance, 
though less intensely than the chromatin. He refers to previous 
observations by Flemming and others on this minute structure. 
Origin of the Karyokinetic Spindle.f — Dr. F. Hermann has studied 
this in the spermatocytes of Salamandra. The achromatin spindle 
certainly owes its origin to the cell-substance, to the protoplasm, but it is 
possible that the .achromatin of the nuclear framework has some secon- 
dary share. From the dividing centrosomata to the nucleus contractile 
fibrils are developed, which eventually enter into a secondary connection 
with the achromatin fibres of the nucleus. All the fibrils which exhibit 
contractility belong to the cell-substance. In the central part of the 
completed spindle, fibrils run from polar corpuscle to polar corpuscle 
without entering into connection with the chromatin elements of the 
nucleus. But as a kind of mantle over the central spindle there extends 
another system of fibrils which proceed from the centrosomata to the 
chromatin elements. These do not run from pole to pole, but are 
interrupted by the chromatin elements near the equator. Around the 
centrosomata of the spermatocytes in Proteus anguineus , Hermann dis- 
covered groups of short, curved threads, which he calls archiplasmic. 
Central Corpuscles and Attraction-Spheres.^: — Dr. M. Heidenhain 
finds attraction-spheres and centrosomata in the leucocytes of Salamandra , 
in the medullary cells of young rabbits, in the alveolar epithelium and 
leucocytes of the lung of a pneumonic patient, and describes the varia- 
tions which these exhibit in the different cases. 
Attraction-Spheres in Ccelomic Celis.§ — Dr. 0 . Burger finds, within 
the proboscis-sheath (“ rhynchocoelome ”) of Nemerteans, resting cells, 
each with an attraction-sphere and a central corpuscle. The attraction- 
sphere lies in the long axis of the cell, often towards one end, usually 
by the side of the nucleus which almost always lies to one side of the 
cell. The centre of the attraction-sphere lies very near the nucleus, at 
an almost constant distance. The nucleus was often kidney-shaped, and 
then the centre of the sphere lay in the concavity. Only twice were 
double attraction-spheres observed, and the cells do not appear to 
divide. 
* Anat. Anzeig., vi. (1891) pp. 482-3 (3 figs.). 
t Archiv f. Mikr. Anat., xxxvii. (1891) pp. 569-86 (1 pi. and 2 figs.). 
% Anat. Anzeig., vi. (1891) pp. 421-7. 
§ Tom. cit,, pp. 484-9 (7 figs.). 
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