ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
891 
for months in absolute alcohol, renewed almost daily, exhibited the same 
phenomenon. Cold bichloride of mercury was used as a fixing reagent ; 
Lang’s solution generally destroyed the cuticle. Other fixing materials 
are not suitable for Nematodes, as they affect the subsequent staining. 
To avoid crumpling, the hardening was effected in Schulze’s dialyser, 
after which the pieces were left for some time in absolute alcohol. They 
were then treated, not with xylol, which causes crumpling, but with 
chloroform. This was evaporated in an oven, and paraffin was continu- 
ally added ; when this had set, sections of 3 ^ thickness were cut. 
Sections were stained with borax-carmine or heematoxylin ; gold-chloride 
was used to make the cell-boundaries more distinct. In order to follow 
out the finest details of the nervous system chrom-osmic acetic acid 
was used, followed by acetic, the pieces being about six hours in the 
former, and twenty-four in the latter fluid. 
Investigation of Ctenophora.* — Dr. P. Samassa succeeded, notwith- 
standing the statements of Chun and Hertwig, in making satisfactory 
sections of Ctenophores. He effected this by the celloidin-paraffin 
method which he modified as follows; the object was removed from 
absolute into a mixture of equal parts of ether and absolute ; ordinary 
celloidin was cut up into small pieces, and dried in the oven so as to 
completely remove all the water. Every day a piece was added to 
the alcohol and ether mixture in which the object was, so that after 
ten days the solution was glairy. As the long period of remaining in 
the solution is not in the least harmful to the object, a slow increase 
in the amount of celloidin is much to be recommended, as the danger 
of curling up is thus avoided as far as possible. 
Preparation of Budding Hydroid Polyps, j — The specimens 
studied by Herr A. Lang, which were sent him from Naples, were 
preserved in 70 per cent, sublimate alcohol, those from Genoa were 
partly in absolute, and were partly killed by hot sublimate and pre- 
served in 90 per cent, alcohol. The sections were stained with picro- 
carmine (after Ranvier), alum-cochineal and hsematoxylin ; double 
staining was effected by picro-carmine (in toto ) and subsequently by 
hematoxylin and Lyon’s blue. Alum-cochineal stained the nuclei well. 
The Hydrse were preserved with hot watery or alcoholic sublimate 
solution, and partly with Path’s mixture of picric, osmic, and acetic 
acids. 
Von Koch’s Petrifying Method.J — Dr. C. Rose discusses the method 
of petrifaction which von Koch used in studying silicious sponges, 
corals, and the like, and points out that L. A. Weil, in using it for the 
study of teeth, omitted to “ steam ” very slowly, and thus obtained 
artificial results. For “ Weil’s sheath ” is certainly an artificial pro- 
duct, and can be produced by a misuse of Koch’s ingenious method. 
Observation and Vivisection of Infusorians in Gelatin.§— Herr 
P. Jensen finds, as Prof. Stahl suggested, that a gelatin solution is 
most useful for studying infusorians and the like. Their movements 
* Arch. f. Mikr. Anat., xl. (1892) p. 158. 
t Zeitschr. f. Wiss. Zool., xlv. (1892) pp. 3 66 and 7. 
t Anat. Anzeig., vii. (1892) pp. 512-9, 
§ Biol. Centralbl., xii. (1892) pp. 556-60. 
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