THE DEVELOPMENT OE ALCYONIUM DIG1TATUM. 
59 
6. Food. 
This appears to be almost wholly animal. In only one 
instance was evidence found of any vegetable matter being 
ingested — when a desmid was seen embedded in an endoderm 
cell in one of the ventral mesenteric filaments. The polyps 
reached quite an advanced stage of development while simply 
using* up the embryonic yolk. Several pinnules had developed 
before this was exhausted, in bowls to which no food had been 
added. Cultures of Nitzschia, Pleurococcus, and other very 
small green algae were tried as food with no success. Very 
fine plankton was added regularly to some bowls and to the 
water of the rearing tank, as adult colonies are known to 
thrive on Nauplii and small Copepods (12), and on this food 
the polyps developed six to seven pinnules, and small 
colonies were produced. The reddish remains of a fairly 
large copepod was one day found in a polyp, and on two 
other occasions Temora longicornis was swallowed, while 
Balanus nauplii were also accepted. However, those 
polyps kept in Cawsand Bay flourished best, and while in the 
laboratory for examination were frequently seen catching and 
swallowing the larvae of Leptoclinum, which was also growing 
on the dishes. They were successfully fed with these larvae 
and with similar larvae of Botrylloides, from a pipette, and 
would also take adult individuals removed from these colonies 
when they were offered. The larvae were swallowed head 
first, and the red Botrylloides larvae could be traced excel- 
lently. Stages in the swallowing and disintegration of food 
exactly like those figured by Miss Pratt (12) were obtained. 
The young colonies showed no evidence of being preyed upon 
on the raft, nor did the settled polyps in the laboratory tanks, 
although shrimps ate the eggs and swimming larvae readily. 
It was interesting to find a parasitic copepod in the ccelen- 
teron of the polyps of the female colonies feeding on the 
eggs. 
