ZOOLOGY AND BOTANY, MICROSCOPY, ETC.' 379 
and tliat the fault lies in the acetic acid, which causes shrinkage of the 
nucleus and destruction of its delicate reticulum. Chromic and osmic 
acids alone, when the chromic is not too strong, have a good effect, but 
at the same time have the disadvantages of contracting the nucleoli, 
preventing staining, and making the yolk hard and brittle. 
Examination of Nephridia of Phylactolsematous Polyzoa. * — 
Mr. A. Oka, in his investigation, first stupefied the colonies with a fluid 
prepared after Cori’s receipt (10 per cent, solution of methyl-alcohol 
in 0*75 per cent, salt solution with a few drops of chloroform), and then 
fixed them with Flemming’s fluid. After washing in rain- water they 
were gradually hardened in alcohol. For staining he used Boehmer’s 
hosinatoxylin, sometimes in connection with alcoholic solution of eosin. 
The stupefying fluid used seems to work especially well upon such forms 
as these. 
Examination of Segmenting Ova of Isopods.f — Prof. J. P. McMur- 
rich recommends, for developing eggs of Isopods, fixing in alcoholic 
picro-sulphuric acid, staining in Kleinenberg’s hematoxylin, and washing 
in acid alcohol until all the stain is removed from the yolk. The egg 
should then be cleared in oil of cloves, and examined as a transparent 
object. 
Study of Young American Sponges.J — Mr. H. V. Wilson found 
that the young Esperella is, after metamorphosis, so thin that it 
cannot be scraped off the dish without injury. He therefore coated the 
dishes with a thin layer of paraffin ; collodion was also used. For fixing 
purposes, he found that very much the best fluid was the mixture of 
acetic acid, alcohol, and osmic acid recommended by Zacharias. He 
allowed this to act for from 10 to 20 minutes. Kleinenberg’s picric 
method was of use for special points, as it often preserved the individual 
cells in a more natural and uncontracted condition than the Zacharias 
fluid, hut in general it disassociated the elements too much. 
A new Method of Entrapping, Killing, Imbedding, and Orienting 
Infusoria and other small objects for the Microtome.§ — Mr. J. A. 
Ryder, feeling the want of a reliable method for this purpose, has, after 
trying a number of devices, hit upon a plan that is not only very simple, 
but is also capable of wide application, since organisms as small as 
12-5 p. in diameter may be cut and held. He makes a filter from thin 
slices of elder-pith, which are perforated at pretty regular intervals by 
openings caused by cutting through the very thin cellulose walls of 
certain of the pith-cells. A good supply of the little pith-filters should 
be cut, and kept in stock in a pill-box ready for use at any time. The 
next step is to take some ordinary good white filtering-paper cut in discs 
or squares about 1 in. in diameter. 
A small drop of water on the end of a wooden toothpick should be 
used to moisten a point at the centre of one of these paper discs or 
squares, so as to make a damp area just about the area of one of the 
discs of pith. A wire 1/16 in. thick should be heated at one end, and 
with it some melted paraffin should be placed on the paper disc. This 
* Zool. Mag., 1895, pp. 25. f Zool. Anzeig., xviii. (1895) pp. 109-11. 
t Journ. Morpbol., ix. (1891) pp. 286 and 7. 
§ Amer. Natural., xxix. (1895) pp. 191-8 (1 fig.). 
