320 
MAYNARD M. METCALF 
EXPLANATION OF FIGURES 
13 At 2:58^ p.m. These two vacuoles are about to fuse. 
14 At 2:59| p.m. The two vacuoles have fused and the resultant single vac- 
uole has somewhat enlarged. 
15 At ^ minute past three. Another very small vacuole has appeared among 
the granules. 
16 At 3 :08 p.m. The vacoule has reached nearly full size. It is now surrounded 
by a single layer of granules. The four small vacuoles in the cytoplasm near 
the contractile vacuole did not fuse with the contractile vacuole, but remained 
unmodified near it. They were not drawn in the next three figures, though they 
were present. 
17 At 3:16 p.m. The contractile vacuole has enlarged a little, has pushed 
through most of the ectosarc and is almost touching the pellicle. Its granules 
have been pushed aside from the point where the vacuole is to meet the pellicle. 
18 At 3 :17 p.m. The contour of the vacuole and the pellicle now coincide. 
19 At3:17ip.m. Immediately before the rupture of the pellicle and the con- 
traction of the vacuole. 
20 At 3:23 p.m. During the. five and a half mintues that intervened be- 
tween the condition shown in the last figure and that shown in this figure, the vacu- 
ole contracted, leaving its mass of granules in contact with the pellicle. Several 
small vacuoles have appeared and have fused, till now we have one small and two 
large vacuoles. 
21 At 3:27| p.m. The single vacuole, the result of fusion, has not reached its 
customary full size, but is already in contact with the pellicle. 
22 At 3:34 p.m. The vacuole is larger and is now ready to contract. 
23 At 3:35 p.m. The vacuole is contracting, it having almost entirely dis- 
appeared. Even in this condition with the position of the pore so clearly shown 
by the shape of the vacuole, I failed to see the actual pore. I do not doubt it was 
of the full size indicated by the outlet tube, but one could not focus so accurately 
on the pore itself as to escape the impression of the pellicle above and below the 
pore. I have drawn this as it appeared, as if stretched across the mouth of the 
outlet tube. One cannot doubt however that there was here an actual pore. 
