302 EDITH M. PRATT. 
Frepinc EXPERIMENTS ON ALCYONIUM. 
E 
Several freshly taken and apparently healthy specimens 
of Alcyonium were placed in wooden tanks, through which 
a gentle but constant stream of filtered sea water was 
running. Conditions of light and temperature were carefully 
observed and maintained as nearly normal as possible; the 
temperature of the water in the tanks never fell more than 
two degrees below, and never exceeded that of the sea. 
Several colonies were also kept in tanks of unfiltered 
sea water and submitted to the same treatment. 
At the end of forty-eight hours most of the zooids of all 
the colonies were seen with their tentacles completely 
extended, and were found to be very sensitive to contact. 
A fairly well-grown colony was transferred from filtered 
sea water to a glass vessel containing a concentrated surface 
tow netting consisting chiefly of Nauplii, small Copepods, 
Daphnids, and Diatoms. The colony quickly recovered from 
the transference, and, at the end of half an hour, the ten- 
tacles, with their delicate fringes of pinnules, were again 
extended. 
A nauplius, actively swimming so near a tentacle as to 
lightly brush against the pinnules, was instantly captured by 
them and paralysed by the innumerable poisoned threads of 
the nematocysts, and in a very short time the surface of the 
tentacles was dotted with hundreds of paralysed Nauplu and 
Copepods. Occasionally a tentacle would curl inwards and 
deposit its captured prey within the mouth. Usually, how- 
ever, the zooids, with tentacles outspread, remained expanded 
for quite an hour, then the colony slowly contracted, and, at 
the end of a second hour, all the zooids were withdrawn 
below the surface. 
Fifteen hours later the zooids began to slowly expand, and, 
when expansion was almost complete, the colony was fixed 
