580 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Structure of Nerve-cells. — Dr. Emil Holmgren* has continued his 
observations on this subject, and finds that the intracellular vessels and 
nerves which he described in Lophius are also to be found in many 
other Vertebrates. In the cells of the spinal ganglia of rabbit, dog, 
and cat, "he further finds that the cells of medium size show a wreath 
of canaliculi round the nucleus, with intra- and extra-canalicular zones. 
In the very large cells the canaliculi are more scattered and less 
regularly arranged. The canaliculi appear to be surrounded by special 
walls within the cells. In birds similar appearances were observed in 
the spinal ganglion cells, but the excentric position of the nucleus 
modifies the general relation of the parts. The canaliculi may be 
much branched and very numerous, so as to greatly reduce the amount 
of cell protoplasm. As well as the spinal ganglion cells in birds and 
mammals, cells from other parts of the nervous system also show intra- 
cellular canaliculi, but these were not found in fishes and Amphibians. 
The author considers the canaliculi to be of lymphatic nature. 
The author also describes remarkable rod-like structures found 
especially in the cells of the sympathetic ganglia in birds and mam- 
mals. They seem to be identical with the structures called crystalloids 
by various observers, but Holmgren does not believe that they are of 
crystalloid nature. 
Dr. F. E. Studnicka f states that he has also seen and studied the 
canaliculi and alveoli described by Holmgren. Studnicka has studied 
the structures in the cells of the nervous system of Petromyzon planeri , 
and points out the necessity of clearly distinguishing between the 
canaliculi and the intracellular capillaries of e.g. Lophius. He believes 
that the canaliculi originate from the fusion of vacuolar spaces in the 
cytoplasm, and as to their meaning, is inclined to lay great stress upon 
their connection with the pericellular lymph-spaces. A similar system 
of canaliculi ramifies in the axis cylinder of the large nerve-fibrils of 
the medullary cord of Petromyzon. Such canaliculi no doubt occur in 
the elements of the nervous system throughout the Vertebrate phylum. 
Histology of Blood. J — Dr. Ermanno Giglio-Tos has studied the 
blood of the Ichthyopsida and the Sauropsida with special reference to 
the question of the nature, origin, function, and relations of the struc- 
tures variously called spindle-cells, thrombocytes, blood-plates, &c. For 
these structures in the two groups named he prefers the term thrombo- 
cytes, reserving that of blood-plates for the structures found in mam- 
malian blood. The method employed was to spread a drop of blood on 
a slide, and then dry rapidly in a flame. The dry blood is then covered 
by a drop of a saturated solution of BX methyl-blue in water. This is 
allowed to act for a minute only, and the blood is then washed with dis- 
tilled water, and a cover-slip placed upon it. If the margin of the cover- 
slip is smeared with olive oil, the film of water does not evaporate, and 
the preparation will keep for four or five days. Various attempts were 
made to render the preparations permanent, but the simplicity of the 
method is such that it is better to make fresh mounts as they are 
wanted. 
* Anat. Anzeig., xvi. (1899) pp. 388-97 (13 figs.). 
f Tom. cit., pp. 397-401. 
t Mem. Rea. Acad. Sci. Torino, xlviii. (1899) pp. 143-208 (2 pls.l. 
