THE DEVELOPMENT OF ALCYONIUM DIGITATUM. 
47 
tinuously for several days, until the spawning was com- 
plete. 
On January 3rd, 1913, a spawning colony was placed in a 
beaker of water and closely watched from 11 a.m. to 3 p.m. 
The majority of the polyps were expanded while their ten- 
tacles were half retracted ; others were only partly expanded 
(c.f. Text-fig. 1). Five eggs were successively extruded 
at regular intervals from the mouth of one polyp during a 
period of fifteen minutes. They passed up the stomodaeum 
one by one and after escaping from the mouth remained in 
contact with the tentacles and oral surface until some slight 
Text-fig. 1. 
Solitary polyp, lateral view. Tentacles retracted, body slightly 
contracted. This also illustrates the appearance of the colonial 
polyp while spawning. 
motion of the water finally dislodged them, when they floated 
upwards. In some cases several eggs were seen in the stomo- 
dseum simultaneously, one below the other, and in squeezing 
upwards through this narrow tube they became temporarily 
•oval but regained their round shape after extrusion. The trans- 
parent membrane which surrounded them before spawning, 
and which always envelops eggs taken forcibly from the mesen- 
teries, was thrown off during the process of spawning, and the 
empty membranes were ejected into the water after the ova. 
Although artificially fertilised ova did in some cases seg- 
ment satisfactorily, it was found more practicable for rearing 
on a large scale to collect the fertilised ova from the tank 
where they were naturally spawned and fertilised. To do 
this the water was siphoned over into white dishes, from 
which the eggs were removed with a pipette. 
