THE ROLE OF MUCUS IN CORALS. 595 
with non-nutritive particles. With a pair of forceps or bent 
needle one can lift up or detach a stream, when it is found 
that the fluid is viscid, and presents all the usual character- 
istics of mucus. 
The continuance of both the inhalent current and the 
streams of mucus is found to be altogether dependent upon 
the amount of the nutritive solution. When the pigmented 
meat extract is weak an inhalent current is nevertheless set 
up, but ingestion continues for only a short time, and then 
Fic. 3.—Distribution of nutritive particles over the disc of 
Fungia; streams of mucus are formed around the mouth and 
carry the particles down the stomodexum. 
the flow stops; the reaction has ceased with the exhaustion 
of the supply of the nutritive solution. After a time the 
mouth opens and the stomodzeal current is renewed, but in 
an opposite direction, and any non-ingested pigment particles 
remaining on the disc are then wafted outwards over the 
edge. Moreover, when shreds or patches of mucus are being 
floated away over the disc the direction of their movement 
can be readily reversed by the addition of nutritive solutions 
around the mouth. Upon the application of the stimulus 
the outward movement of the objects at once ceases, and they 
then begin to move slowly towards the mouth, where they 
are ingested. Should the indrawal not be completed before 
the action of the nutritive juice ceases, the bodies come to 
