Preserved specimens were generally used and the dissec- 
tion was performed under 70 per cent. spirit.” The 
specimen was opened in the usual way and pinned out on 
a piece of weighted cork in a small glass dish, and the 
alimentary canal carefully removed. The specimen and 
the cork were then put into stain, either carmine or 
Mayer’s acid hemalum, for 12 to 24 hours. After the 
excess of stain had been removed the worm and the cork 
were passed into 90 per cent., and then into absolute 
aleohol. The body wall, which by this time was 
moderately certain to retain its shape, was unpinned, and 
after another change of absolute alcohol was placed in oil 
of cloves and afterwards mounted in balsam. Fig. 25 was 
drawn from such a preparation, in which the blood-vessels, 
&c., are very clear. Useful preparations may also be 
made by splitting the anterior portion of preserved 
specimens into two by a median sagittal cut. Such 
sections give a good idea of the position and relations of 
the nuchal organ, diaphragms, proboscis, &e. 
Preparations of the Ceelomic fluid may be made thus. 
Immediately after the fluid is removed from the animal 
spread a small drop evenly over the middle of a glass 
slide so that it forms a very thin film. This may be 
treated in either of the two following methods : — 
(1) Invert the slide so as to bring the film over the 
mouth of a bottle containing glacial acetic acid and hold 
it there for several seconds. The vapour of the acid will 
kill and “fix” the cells, ¢.c., will coagulate their proto- 
*“If a fresh worm be used, after the dissection under sea water has 
been completed, the specimen should be ‘“ fixed’’ in a saturated 
solution of corrosive sublimate. In this case, however, the dissection 
should be pinned out with cactus needles, and not with ordinary pins, 
as the latter would produce a deposit of mercury in the neighbouring 
tissues. After fixation wash in water and in 50 per cent. and 70 per 
cent. spirit, until all traces of sublimate are removed. Then stain as 
directed. 
