THE MICROTOMIST' S VADE-MECUM

Saturated picric-acid solution . . 100 vols. witb p
,     sulphuric acid                 2   ,,              d
Water           .    .    .    .     . 600   ,,ti
This liquid is for larve of Echinodermata, of Medusoe, and of     fol
Porifera; for Rhizopoda and Infusoria, add two or three drops      Stat0t
of 1 per cent. acetic acid for every 15 c.c. of the liquid. The    ter
acetic acid is added in order to bring out the nuclei and          1061
" nucleoli."  Blanc fixes under a cover-glass, notwithstanding     0
the objections of Korschelt. Wash out with 80 per cent.
alcohol, followed by 90 per cent. and absolute. Stain with         N01
saffron solution (Formula No. 106), wash out with 80 per          0i hr
cent. alcohol until the colour is sufficiently extracted, and pass  thei
through absolute alcohol into clove oil.                          IuXOV
Blanc recommends the method for the preservation of most         ilst
microscopic organisms, and in particular for marine Nema-          dIlst
toda, the stain being sufficiently penetrating to pass through     at ti
their thick chitinous integument.
645. Gaule's " Wiirmchen " (or " Cytozoa ") (Drepanidium         ailf
ranarum, LANKESTER) (Gaule's method').-Choose a medium-           iUGP'
sized vigorous frog, with clear eyes and lively movements.         he
(Gaule's experiments were chiefly made with R. esculenta.)        ad SiI
The frog must not have been long kept in confinement, and ninGl
he must have been kept in a warm place for some hours solutic
before the experiment. Prepare a stoppered glass cylinder eells
containing a few c.c. of quicksilver and 5 c.c. of 0'6 per cent. hs
salt-solution. With scissors make a cut from the tympanum          ten
of the frog on either side towards the backbone (do not incise     potas
the backbone), and allow the blood to flow into the salt-solu-      Go
tion. As soon as the blood gets to drop slowly the frog may        ceont
be killed and thrown away. Then close the cylinder and             went
agitate for a few moments, until the quicksilver appears          coloi
broken into very fine drops on the sides of the vessel. Allow     Jcied
the quicksilver to settle, remove a drop of the supernatant
fluid with a pipette, mount it on a slide, and close the cover
I ' Arch. Anat. u. Phys.,' 1880 (Phys. Abth.), p. 00.

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