THE DEVELOPMENT OF ALCYONIUM DIG1TATUM. 
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polyps lived in finger-bowls in the laboratory for about three 
months, but eventually died without forming colonies. They 
seemed healthiest when the bowls were immersed in much 
larger cylinders of sea-water, with the growth of algse and 
diatoms checked by limiting the amount of light, and with 
frequent changes of water. In finger-bowls through which 
air was constantly bubbled the polyps were nearly always 
expanded, but in others they were nearly always closed until 
dusk, although they usually opened if the bowls were removed 
from their containing cylinders for examination. Hence the 
polyps seem sensitive to light, currents in the water, and 
temperature. No regular alternation of the expanded and 
contracted stages was observed. 
5. Colony Formation. 
Some of the polyps produced one bud in the laboratory, 
and one produced two daughter polyps. The finger-bowls 
were difficult to keep clean, as the algae and diatoms in the 
fine townetting, which was added from time to time as food, 
settled down rapidly as a thick greenish coating. Therefore 
at this stage, as it seemed unlikely that the colonies would 
continue to develop in the laboratory, two bowls containing 
numerous solitary polyps and young colonies were taken out 
on March 17th, 1914, to Cawsand Bay, just outside Plymouth 
Sound, to continue their growth. They were fastened in 
wicker stands which were suspended inside a box-like raft 
into which the sea penetrated, and were brought in tem- 
porarily for examination on the following dates, after which 
they were always returned : 
(1) April 30th, after one and a half months on the raft. 
(2) July 15th, after four months on the raft. 
(3) September 16th, after six months on the raft. 
This experiment was entirely successful, and the polyps 
gave rise to disc-shaped colonies in the early stages of which 
the new individuals arose according to a definite plan. As 
the polyps increased in number the parent individuals seemed 
