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I treat as small pieces as possible with the fluid (in not too small 
quantities) for 12 to 24 hours, or sometimes even longer (2 — 4 days), 
they are then washed and may now, directly enclosed in paraffin (not 
imhedded), easily be cut, under water or alcohol, on the microtome ; if 
necessary the pieces may also be hardened in alcohol. If cut with 
a sharp knife, one obtains in this way really brilliant sections. I 
have even got sections only .005 mm. thick. The sections are 
stained in different ways, carmine, hæmatoxylin (Delafields, Wei- 
GERTs or Heidenhains solutions) or coal-tar colours (eosin, nigro- 
sin, methylen-blue, etc), or combinations of these different staining 
methods are used. 
As a, for many purposes, really excellent combination, it may 
be recommended first to stain' the sections in an aqueous solution of 
hæmatoxylin ('/2 *^/o) foi" some hours or longer, then wash out and 
treat the sections for a day (or longer) in a solution of potassium- 
bichromate (.5 — i ^Vo); afterwards, wash out again (not too much) 
and stain in Delafields hæmatoxylin ') ; if overstained, decolour in 
water to which a fe w drops of acetic a eid have been added. The 
sections are examined in glycerin (50 — 100 ^o) or in canada bal- 
sam. The preparations obtained in this way are, indeed, in many 
respects superior to any others. 
As however the method is certainly somewhat complicated, I 
prefer, when possible, to stain in toto. This affords very good results 
when the pieces are sufficiently small, and are treated carefully. In 
this case, of course, a longer time is necessary for staining, de- 
pending on the size of the pieces. Delafields hæmatoxylin I generally 
employ very diluted, for staining in toto. 
Another method, which affords excellent results for some pur- 
poses, is fixing and hardening in alcohol gradatim. Especially 
for Annelids, it is very good first to narcotise the animals, by 
carefully pouring a thin layer upon the surface of a small portion of 
seawater in a glass in which they live. When narcotised they are 
stretched on a waxplate and hardened in alcohol gradatim. When 
sufficiently hardened, (not too much) they are stained in a water}' 
solution of hæmatoxylin, and afterwards treated with potassium- 
bichromate as originally recommended by Heidenhain. For some 
purposes fixing in a saturated watery solution of picric acid is still 
better, then washing out in diluted alcohol and staining as above, 
^) As will be seen this method is very like that already recommended by 
Flemming, for staining of glands. Zeitschr. f. wiss. Microscopie Bd. IL 1885 p. 517. 
