250 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
as may be wished, when it is ready for sectionizing. Sections were 
made with one of Dumaige’s automatic microtomes, which gives the 
most excellent results. When fixed, the specimen was stained with 
picrocarminate of ammonia, which is the best of all ; after one or two 
days in a solution of this material, the preparation must be gradually 
hardened in alcohol of 70°, 90°, and 100° — one day in each, fresh 
absolute alcohol being applied two days in succession. To this last 
fluid methylene-blue may be added, as it will stain the protoplasm and 
muscles, while having no influence on the nuclei. The object should 
next be successively placed in cedarwood-oil, paraffin with this oil, and 
pure paraffin. As the renal cells of Molluscs are very small, the sections 
should be extremely fine, and it is well not to have them more than 
1/dOO mm. in thickness. 
When about to be placed on the slides it is well to make a limpid 
solution of 2 or 3 parts of gelatin in 100 parts of water; this, after 
careful filtration, should be placed on the slide, and the rows of sections 
will be found to swim in it ; they can then be arranged as desired. 
The slide must then be placed on a plate warmed to about 40°, but not 
hot enough to melt the paraffin. At this gentle heat the sections become 
spontaneously extended in the gelatin, and all the creases in them will 
be found to disappear. The gelatin may now be left to dry. When 
the gelatin is dry, the paraffin may be easily dissolved away and the 
sections mounted in balsam. 
Mode of Preparing 'Ova and Embryos of Blatta Doryphora.*— 
Mr. W. M. Wheeler used the following method in his studies on Insects’ 
eggs : — The ovarian ova in all stages up to maturity were dissected out 
in normal salt solution, and hardened for fifteen minutes in Perenyi’s 
fluid. They were then transferred to 70 per cent, alcohol, which was 
changed several times at intervals of an hour, and were finally preserved 
in alcohol of the same strength. When stained with borax-carmine and 
sectioned, the yolk retained none of the red stain, while the chromatin 
of the nucleus shone out as a glistening deep red spot. Perenyi’s fluid 
rendered the chorion of the mature ovarian egg pervious to borax- 
carmine. Hardening in a saturated aqueous solution of corrosive sub- 
limate gave good results with young ovarian eggs. Oviposited eggs 
were killed by placing the capsules in water slowly heated to 80°-90°C. 
The two lips of the crista of the capsule were then separated by the aid 
of fine forceps, and pieces of the walls torn away, till the eggs could be 
easily pushed out of the compartments formed by their choria. The ova 
thus isolated were either transferred directly through 35 per cent. 
(10 min.) to 70 per cent, alcohol, or they were left for 15 minutes in 
Kleinenberg’s picrosulphuric acid, and after repeated washing in 70 per 
cent, alcohol, preserved in alcohol of the same strength. Both methods 
gave equally good results. 
Though he has succeeded in dissolving the chitin of the ootheca with 
sodium hypochlorite, the method of tearing off the walls after heating to 
80° C. gave such satisfactory results that he adhered to it through his 
work. He has found Grenacher’s borax-carmine in every way the most 
expedient and reliable staining fluid. Eggs and embryos, up to the time 
* Journ. Morphology, iii. (1889) pp. 292-3. 
