108 SPONGES 
specimen must be at once removed from the water and 
placed in a 50 per cent solution of alcohol in which it 
must remain for 24 hours, then placed in a g5 per cent 
solution, where it may be kept permanently, unless the al- 
cohol becomes stained with fluids emitted by the sponge, 
in which case, the alcohol should be changed as often as 
the staining occurs. 
Formalin cannot as yet be used successfully in pre- 
serving sponges, but further experiments ae it may prove 
Caer 
small sponges for biological and histological work 
may be placed ina saturated solution of picric acid from 
which they must be removed in twenty-four hours, and 
placed in alcohol which must be changed as long as it be- 
comes stained. 
Sponges so treated may be embedded in_paraffine, 
sectionized and mounted, or stained and mounted for mi- 
croscope slides. 
