6 SPONGES 
Show specimen which has been preserved in alcohol 
to illustrate sponge flesh. 
Then by the aid of this and cut sections of skeletons, 
and model of section of a sponge, show the cilia cells, and 
a blackboard sketch of cilia, and also of the water system 
(see page 13) and ‘compare cilia with pseudopoda of amoe- 
ba (see page 15.) 
Let the pupils make drawings of all the parts possible, 
in order to fix the subject upon their minds. 
Show Tube Sponge with dried flesh. Show closing’ 
membrane and cloacal tube. Illustrate budding of sponge. 
Show skeleton of Tube Sponge, and explain growth 
by blackboard drawing. Show microscope slides of fiber 
with hollow center and arrested growths. Show that old 
fiber cannot anastomose, nor new with old, except by sold- 
ering. (See page 27.) Have pupils make drawings, illus- 
trating these parts. 
Show fiber of Horny Sponges. 
Give an account of the method of preparing Horny 
Sponges. 
