598 J. E. DUERDEN. 
If shreds of meat from which all the juices had been 
extracted were placed near the lips they either brought 
about a feeble reaction or none at all, while pieces of paper 
soaked in meat juices served as stimuli just as effectively as 
meat itself or meat extractives. It was thus plainly demon- 
strated that the opening of the mouth, the institution of the 
inhalent current, and the copious exudation of mucus were 
altogether due to the nutritive extractives, irrespective of 
any mechanical stimuli. 
SToMODEHAL CURRENTS. 
With regard to the wafting away of certain objects from 
the oral disc, and the indrawal of others, the above experi- 
ments prove conclusively that in Fungia there is at times a 
current of water flowing from the mouth, and that the 
direction of this current can be reversed by nutritive 
substances or their extractives. Such currents are produced 
by the lining of cilia always strongly developed along the 
whole stomodeal surface of polyps. Parker,! in the experi- 
ments with Metridium, invariably found the direction of 
the current over the lips to be outward in quiescent animals 
with the mouth open, while it is reversed when pieces of 
crab meat are applied to the lips; Carlgren’s? experiments 
with other actinian species indicate similar changes in the 
stomodeeal currents. 
At first it seemed scarcely possible that any ciliary current 
from the mouth could influence such a large surface as that 
of the disc of the mushroom coral without any assistance 
from either discal or tentacular cilia, but the following 
considerations appear to leave no doubt that such is the 
case. When the mouth is completely closed no movements 
1 <The Reversal of Ciliary Movements in Metazoans,” ‘Amer. Journ. 
Physiol.,’ vol. xiii, 1905, p. 2. 
2 Uber die Bedeutung der Flimmerbewegung fiir den Nahrungstransport 
bei den Actiniarien und Madreporarien,” ‘ Biol. Central.,? Bd. xxv, 1905, 
p. 308. 
