596 J. KE. DUERDEN. 
rest, and are a second time wafted outwards upon the 
reversal of the current. On an active polyp it is thus 
possible, by the application of limited supplies of meat 
juices, to change a number of times the outward or inward 
movement of the mucus and embedded particles over the 
disc. Parker,}in experimenting with pieces of the lip of 
Metridium, also found that the ciliary reversals which 
bring about the change in direction of the current could be 
repeated many times without impairing the tissues. 
As the mouth in Fungia is rather large, it is possible, by 
means of a fine pipette, to apply meat juice over any restricted 
region without its spreading to the neighbouring parts. It 
is then found that an inhalent current is set up over the area 
to which the solution is applied, while elsewhere an exhalent 
current is in progress. ‘he phenomenon is thus presented 
of streams of mucus being indrawn over one portion of the 
polypal disc, while shreds of mucus are being wafted towards 
the margin over the remaining part of the disc. 
If, instead of numerous small particles, a fragment of meat, 
a few shreds of crab’s muscle, or a piece of an annelid is 
placed upon the disc of Fungia it causes a momentary 
depression of the disc and tentacles among which it falls, 
but recovery takes place almost as readily. The juices from 
the food soon diffuse to other parts of the discal area, and, 
on reaching the mouth, the latter responds by opening 
widely, and, at the same time, an inhalent stomodzal current 
is established, which leads to the formation of the mucus in 
streams. Should the fragment be small it is drawn some- 
what quickly over the disc as part of the inflowing current 
without any assistance from the tentacles, and, on reaching 
the mouth, it can be seen to glide directly downwards without 
coming into contact with the lips or stomodeal walls. The 
latter take no direct part in the swallowing. After ingestion 
the mouth closes, and neither incurrent nor excurrent can be 
detected for some time unless further stimuli be applied. 
1 «The Reversal of Ciliary Movements in Metazoans,” ‘Amer. Journ. 
Physiol.,’ vol. xiii, 1905, p. 3. 
ee 
