118 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
to which, in Mr. MacBride’s opinion, Cuenot has not paid sufficient 
attention. Very thin sections — 3^ p,, 4J- p, and for adults and oldest 
stages 7 p — were made. The author states that he obtained perfect 
series of sections with finely differentiated stain, and clear, sharp 
outlines; the sections are said to be clearer and more diagrammatic 
than the figures he has been able to make of them. 
Preparation of Larvae of Asterias vulgaris.* — Mr. G. W. Field 
found that Kleinenberg’s picric salt gave the most satisfactory results 
for billing these larvae. Flemming’s, followed by Merkel’s fluid, gave 
excellent results, as did also Perenyi’s fluid. Oil of cedar or of origanum 
proved most satisfactory for clearing. 
Preserving Cunina.f — Dr. 0. Maas killed the Cunina - stock and its 
buds with Flemming’s chrom-osmic-acetic acid (5-20 minutes), gradually 
washed them with water, and passed them through a series of dilutions 
of alcohol up to 90 per cent. Thence some were replaced in water and 
stained with borax-carmine, but the unstained forms gave best results. 
Methyl-blue was also used to demonstrate the nervous system. The 
most important point is to see that the medusae are properly placed 
before they are cut. 
Preparing and Staining Yeast.J — Dr. H. Moeller used for fixing 
yeast preparations a 1 per cent, solution of iodide of potassium saturated 
with iodine, this fluid ten times diluted, and also iodine-water. The 
material and the fixative may be mixed together at once or upon the 
cover-glass, which merely requires a smear. When fixed and dried 
the preparation must be thoroughly hardened. This may be done by 
leaving the preparations in the iodine solution for a day, and then after 
washing in water and weak spirit keeping them in absolute alcohol for 
one or two days. The time required for hardening may be diminished 
by repeatedly boiling the alcohol, and the preparations are more clearly 
stained if they are then immersed in chloroform for a day. It is always 
useful to pass the cover-glasses once or twice through the flame. 
The preparations are best stained by means of haematein and picric 
acid, the latter acting as a mordant. But it is essential that the prepara- 
tions should be thoroughly fixed and hardened ; they may then be 
treated with a saturated aqueous solution of picric acid for 1/2-3 hours ; 
the preparation is then passed through water so as to wash off some, but 
not all of the picric acid. For staining, an alkaline solution of hema- 
toxylin is used. It would not appear, however, that the foregoing 
staining was more advantageous than that with anilins, of which the 
following were successfully employed : — phenolfuchsin, alkaline methy- 
len-blue, Gram’s method, and also gentian- violet in carbolic acid, water, 
glycerin, 1 per cent, acetic acid, and 1 per cent, iodide of potash. 
If the anilin dyes are used the preparation should be over-stained 
and then differentiated by some decolorant ; if Gram’s method be 
adopted alcohol must be used ; but for other stains a mixture of equal 
volumes of glycerin and water was found to give the best result. As 
soon as the desired degree of decolorization is attained the preparation 
* Quart. Joum. Micr. Sci., xxxiv. (1892) p. 106. 
t Zool. Jahrb., v. (1892) pp. 271-300 (2 pis.). 
j Centralbl. f. Bakteriol. u. Parasitenk., xii. (1892) pp. 537-50 (1 pi.). 
