308 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
that the reader may judge for himself of their resemblance to nuclear 
figures. 
Structure of Nerve-Cells and their Processes.* — Prof. A. S. Dogiel 
has continued his investigations on this subject, with especial reference 
to the retina. The nerve-cells of the retina are of three types : — ( a ) 
cells with protoplasmic processes and an isolated axis-cylinder process 
which passes directly into the axis-cylinder of the nerve-fibre ; (h) cells 
with protoplasmic processes and one axis-cylinder process, which breaks 
up into fine branches and threads ; (c) cells with only protoplasmic 
processes. An axis-cylinder of a nerve-fibre begins (1) directly from a 
cell or from one of its protoplasmic processes, or (2) from the network 
of the second type of nerve-cell ( b ), or (3) directly from the branches 
and threads of the protoplasmic processes of the third type of cell 
(c). The protoplasmic processes of the nerve-cells of the retina unite 
in a network connecting the cells of one type. Like the axis-cylinder 
processes the protoplasmic processes have a nervous character. The 
cells and their processes have fibrils and interfibrillar substance, and 
some of the fibrils of all the protoplasmic processes of a cell pass into 
the axis-cylinder. To the nerve-cells belong higher nervous and pro- 
bably trophic functions. The nerves cannot be considered as isolated 
elements. 
Giant-cells of the Medulla and their Central Corpuscles, t — 
Herr M. Heidenhain finds in the resting giant-cells of the red osseous 
medulla in the rabbit numerous central corpuscles, in many cases over 
100 in one cell. In one very large pluripolar mitotic figure there 
were 135 ! So many form a main group in the endoplasm, while 
others form one or several accessory groups in the first zone of the 
exoplasm. For further notice we await the promised publication of 
figures and full details. 
Weil’s Basal Layer of Odontoblasts. :J — Dr. C. Bose devotes a con- 
siderable amount of space to a demonstration of the non-existence of 
this layer except as an artificial product. 
Contractile and Conducting Primitive Fibrils. § — Prof. St. Apathy 
believes that the primitive fibrils of smooth muscle and of nerve have 
been hitherto overlooked ; the interfibrillar spaces have been seen, not 
the fibrils. By Apathy’s gold method, the details of which are not 
given, the fibrils may be seen dark violet against the pale red inter- 
fibrillar substance. The fibrils are not stained with the usual anilin 
dyes. 
Apathy finds that a smooth muscle-fibre (of Hirudinea) shows clear 
and dark bands. The essential difference between the two kinds of 
fibre is that in the smooth fibre the elementary fibrils are straight and 
parallel to the longitudinal axis, while in the striped muscle they run in 
undulating lines. Hay craft’s varicosities the author believes to have 
been artificially produced. 
When the optical characters of myelin predominate in a nerve, the 
* Arch. f. Mikr. Anat , xli. (1893) pp. 62-87 (2 pis.). 
f SB. Physik.-Med. Gesell. Wurzburg, 1892. pp. 30-3. 
% Anat. Atizeig., viii. (1893) pp. 272-85 (5 figs.). 
§ MT. Zool. Stat. Neap., x. (1892) pp. 355-75 (1 pi.). 
