462 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
primitive duct of the liver. Subsequently there is a union of the three 
parts. The duct of the dorsal portion degenerates ; the ducts of the 
two ventral parts unite in a common terminal region (ductus Wirsungia- 
nus), which opens first into the ductus choledochus, but ultimately into 
the gut. 
In the sturgeon there are four rudiments of the pancreas, as v. Kupf- 
fer has shown ; in Amphibians there are three ; in the chick (according 
to Felix) there are three ; in at least some mammals there is a dorsal 
and a ventral rudiment. It is probable that the fourfold origin, as seen 
in the sturgeon, is the primitive condition, and that the most posterior 
portion has in most cases been dispensed with. 
£. Histology. 
Attractive Sphere.* — Dr. 0. Van der Stricht, after a short historical 
introduction, gives an account of his observations on the attractive 
sphere in the eggs of Triton , and in cartilage cells. In the former some 
differences were observed from the phenomena described for the Trout 
and for Siredon ; in the eggs of Triton the division of the attractive 
sphere is, ordinarily, effected during the quiescent stage of the nucleus, 
rarely in the anaphase of the mother-nucleus, and exceptionally in the 
metaphase. The author’s account of what he observed in cartilage-cells 
cannot unfortunately be lucidly reproduced without copies of the figures 
to which he frequently refers. 
Nuclear Division in Cut Nerve-fibre s.f — Dr. G. Bizzozero points 
out, in correction of a paper by 0. von Biingner, that the late Dr. A. A. 
Torre discovered in 1884 the mitotic multiplication of the nuclei of 
Schwann’s sheath. This multiplication is exhibited along the whole 
course of the peripheral stump of a cut nerve, and the resulting cells are 
able to absorb the myelin drops which result from the degeneration of 
the fibres. Dr. Torre also showed that in normal medullated nerve- 
fibres the multiplication of nuclei in Schwann’s sheath is mitotic. 
Neuroglia-cells in Peripheral Nerves.J — Dr. E. Kallius finds 
numerous neuroglia cells uniformly distributed throughout the optic 
nerve. Their processes form a very fine-meshed network in the inter- 
stices of which the fibres lie. They were demonstrated in man, horse, 
ox, dog, rabbit, and mouse. Their occurrence corroborates the embryo- 
logical conclusion that the optic nerve is a modified portion of the brain. 
They were also found in the Trigeminal, Auditory, and Vagus, but were 
abundant only at the roots of these nerves. 
Cell-multiplication and Replacements — Prof. J. Frenzel has an 
essay on this subject, the gist of which seems to be expressed in the 
following sentence : — Under the term cell-division we include two 
essentially different phenomena : On the one hand there is cell-multipli- 
cation which by mitosis results in the growth of an organ or of part of 
an organ, and there is cell-replacement which proceeds by amitotic 
division with the result of replacing lost cells. That this contrast, 
* Arch, de Biol., xii. (1892) pp. 741-63 (1 pi.). 
t Arch. f. Mikr, Anat., xli. (1893) p. 338. 
J Nachr. K. Gesell. Wiss. Gotting., 1892, pp. 513-5. 
§ Biol. Centralbl., xiii. (1893) pp. 238-43. 
