890 SUMMARY OF CURRENT RESEARCHES RELATING TO 
which showed both cell-outlines and protoplasmic structure in an 
excellent state of preservation. The objects must remain in the solution 
for from three to fourteen hours, according to the degree of softness of 
the chitin. After hardening in alcohol, the specimens were stained 
with Delafield’s hsematoxylin, and were removed from Flemming’s solu- 
tion to water, and after a few minutes transferred to crude pyroligneous 
acid, where they remained for nearly twenty-four hours ; by this last 
process (von Mahrenthal’s method), the osmic acid is reduced in the 
tissue, and no further staining is required. After dehydration, the 
objects were sunk in chloroform, and then placed for several hours on 
the water-bath in a mixture of chloroform and paraffin, after which 
they were imbedded in paraffin, and cut in the usual way. 
Examination of Nervous System of Ascaris megalocephala.* — 
Herr R. Hesse made transverse and longitudinal sections of this Nema- 
tode. The material, which was fixed by sublimate solution, water at 
60°, chrom-osmic-acetic acid, 1/2 per cent, osmic acid, picrosulphuric 
acid, and 96 per cent, alcohol, was found to be useless, as the nerves 
crumpled up greatly. By chance in one sublimate and one water 
preparation a part of the nerve was not crumpled. In the rest, the 
ganglion-cells were alone made clear by this method. Others which 
were placed fresh, for a day, in 1/2 or 1 per cent, solutions of chromic 
acid, and for a week in chromates, gave poor results when imbedded 
in paraffin, but better when placed in celloidin. The best results 
were got with specimens that had hardened for a long time in alcohol. 
Grenacher’s borax-carmine was used for staining. 
Preparation of Embryos of Strongylus paradoxus. f — Herr B. Wan- 
dollech observed the development of living ova in weak salt solutions 
at a temperature of 30° ; to prevent evaporation the cover-glass was 
surrounded on three sides by wax, while the fourth remained open to 
allow of the addition of fluid. To make preparations of the complete 
egg, a specimen of the worm was placed without any fluid on a very thin 
slide, and cut through in the middle ; the uterus escaped with the fluid 
of the coelom. The slide was next flooded with the fixing fluid heated 
up to 70°. The albumen coagulated, and while the embryos were 
preserved they were at the same time firmly fixed to the slide, and could 
be treated like sections attached by albumen. Borax-carmine was used 
for staining, and it was found necessary to leave the eggs in it for some 
time. In order that the cell-boundaries might be made distinct, Herr 
Wandollech made use of a method suggested to him by Prof. F. E. 
Schulze. On removing the preparations from absolute alcohol, he placed 
them in picric acid dissolved in xylol ; the objection to this method is 
that it requires much practice and patience. 
Examination of Strongylus convolutus.J — Dr. H. Stadelmann was, 
owing to the transparency of this worm, able to make in toto preparations 
of it ; these were put in glycerin, and not in Canada balsam, as in the 
latter reagent specimens become in time quite opaque ; this was not 
owing to insufficient removal of the water, as animals which had been 
* Zeitschr. f. Wiss. Zool., xlv. (1892) pp. 549 and 50. 
f Arch. f. Naturg., lviii. (1892) pp. 127-9. J Tom. cit., pp. 152 and 3. 
