SPONGES 109 
PRA RING SKELETONSTOF SPONGES. 
It is best to prepare skeletons of sponges from fresh 
specimens. The dead sponge is placed in water in a closed 
vessel where it is allowed to remain from forty-eight hours 
to a week or more, depending upon the species; it may 
then be removed with long forceps and carefully washed in 
salt or fresh water. 
Sponge fiber from such specimens may be mounted 
for microscopical study in balsam or glycerine, or the ar- 
rangement of the fiber may be studied with a good magni- 
fying glass. 
Avoid squeezing specimens which are intended for mi- 
croscopical study. It is best to let the water drain out of 
18 
them. Sponges which have been dried with the desh 
on can be macerated, but the process is more difficult, and 
potash must frequently be used to facilitate removing the 
hardened flesh. 
Both fiber and spicules should be boiled before at- 
tempting to mount them upon microscope slides, in order 
to remove all traces of impur ites. 
