752 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
(3) Cutting-, including Imbedding and Microtomes. 
Small Auxiliary Apparatus for the Plate Modelling Method.* — 
Prof. F. Keibel describes a small graving tool which can be attached to 
a microtome in order to mark the 
straight lines in the plate-modelling 
method. The apparatus consists of a 
stout brass hoop B (fig. 97), which fits 
over the knife of the microtome and is 
fixed by the screw S. To this hoop 
is fastened by means of two screws 
(of which only one s is shown in the 
figure) a steel plate p, bent at right 
angles, with its free end pointing 
downwards. On the free end small 
teeth are cut, which are arranged in 
groups and are sharpened on both sides, 
so that their section is as in fig. 98. 
Plate Models of Embryonic Livers.t — Herr J. A. Hammer has 
studied the development of the liver in some Yertebrata by the method 
of plastic reconstruction of the object. The author followed the pro- 
cedure as laid down by Born,J though some departures were made in 
details, perhaps the most important being the use of brown modelling 
wax, which is more plastic than the ordinary uncoloured plates. The 
material was fixed in saturated solution of sublimate and afterwards 
hardened in spirit to which a little iodine has been added. The sections 
varied from 10-20 /x in thickness. The objects were drawn under 
magnifications of 130-150, so that the epithelial cells of the liver, bile- 
duct, &c., were well seen. 
Methods for Examining Embryological Materials — Prof. C. Rabl 
recommends the following procedures for examining the vertebrate 
embryo : — 
Fixing. — (1) Saturated aqueous solution of sublimate 1 vol., satu- 
rated aqueous solution of picric acid 1 vol., distilled water 2 vols. As 
a rule they are kept in this for about 12 hours ; they are then washed 
for a couple of hours, and next transferred to weak spirit. The spirit is 
gradually increased in strength until it becomes absolute alcohol, to which 
a trace of tincture of iodine should be added. (2) Another fixative 
which gives even better results is 1 per cent, platinum chloride solution 
1 vol., saturated aqueous solution of sublimate 1 vol., distilled water 
2 vols. (3) Another mixture, the results of which are sometimes bril- 
liant and sometimes doubtful, is 1 per cent, platinum chloride solution 
1 vol., saturated aqueous solution of picric acid 2 vols., distilled water 
7 vols. Any fixative which contains platinum chloride must be used in 
large quantity and often renewed. With other fixatives the author has 
not obtained such good results, e. g. pure sublimate and Flemming’s 
fluid. Embryos of osseous fishes require to be plunged in hot fixative 
to prevent crumpling of the chorda and rupture of the muscles. 
* Zeitsclir. f. wiss. Mikr., xi. (1894) pp. 162-3. 
t Nova Acta K. S. Sci. Upsaliensis, xvi. (1893) p. 34 (2 pis.). 
X See this Journal, 1884. § Zeitschr. f. wiss. Mikr., xi. (1894) pp. 164-72. 
Fig. 97. 
