A488 A. T. MASTERMAN. 
munication is established between the two chambers, and the 
food particles are ejected in ashower into the intestine. The 
diaphragm then closes up in the reverse manner. The whole 
operation is performed methodically, and takes about fifteen 
seconds to open, a pause, and, perhaps, about the same time 
to close. There are no muscles, and apparently the proto- 
plasmic walls of the stomach and intestine act together im an 
ordinary contraction. 
On the intestinal side of the aperture there is a group al 
cilia of a smaller size than those in the stomach, projecting 
backwards into the cavity of the former. 
Apparently when the diaphragm opens the walls are con- 
tracted up into a belt which depends into the intestine (Fig. 
13), and in this belt region the walls are perceptibly thickened. 
From its upper rim the stomach cilia depend into the intestine, 
and, as a rule, when the aperture closes these cilia are caught 
in this position, but they can be seen to be gradually with- 
drawn, doubled upon themselves, until they are once more in 
their normal position. The movement reminds one of the 
action of a swan bringing its head and neck above water 
(cf. five stages of Fig. 13). 
The intestine (nt.) is a large cone, with the anus at its 
apex. It does not appear to be generally ciliated and its 
walls do not differ essentially from those of the stomach. In. 
its cavity the food-particles are rapidly rotated (Fig. 14). 
Usually the column of water moves up the centre and down 
the outer walls so that the particles pass towards the centre 
ut the anal end. I have seen this current reversed. In 
either case the current appears to be caused by the ring of 
cilia around the pylorus. 
Ciliary motion of a lesser nature also appears to take place 
around the inside of the anus, and a very ring of cilia can be 
often made out in this region. 
The anal aperture (a.) opens in much the same manner as 
the pylorus by protoplasmic contraction of the surrounding 
walls, which draw away from each other till a fairly wide 
aperture is made and the remains of the food are ejected 
