PHENOMENA IN SPONGES. 193 
contract just like the latter, but without ever exhibiting any 
opening. In asimilar way, in detached portions of Spongilla 
several exhalent tubes are occasionally formed. Both in 
these protrusions as well as in other parts of the outer mem- 
brane vacuoles of the size of a cell-nucleus, or even larger, 
may, not unfrequently, be seen to arise, which project above 
the surface, lke the contractile receptacles in Actinophrys 
Eichhornii. 
The remainder of the paper relates more especially to the 
multiplication of sponges by scission; but we are unable to 
perceive that it contains anything novel of importance on 
that subject. 
