THE DIGESTIVE ORGANS OF THE ALCYONARIA. 331 
digestive organs should be very largely supplemented by ob- 
servations of the actual digestive processes in living zooids. 
“Alcyonium digitatum”! provides an excellent subject 
for the study, for not only is it easily obtainable, but the 
transparent nature of the body walls of the arthocodiz 
enables one to observe many of the stages in the digestion of 
food within the living zooid, especially if brightly-coloured 
food material be employed. ‘To obtain a suitable food which 
could be stained by an innocuous colouring matter was found, 
however, to be no easy task. It is well known that food 
material has very seldom been observed in the zooids in col- 
lections of preserved material, while in tropical forms it has 
rarely, if ever, been seen, even in living specimens. In the 
hope of obtaining some information as to the natural food of 
the Alcyonaria, some hundreds of autozooids of genera from 
many localities (including the tropics) were examined, but 
food was observed only in very few instances in the ccelentera. 
It then consisted of small partially-digested masses of organic 
matter, containing fragments of minute crustacea, zoochlorellz, 
and portions of algal filaments, the last-named, however, were 
apparently unaffected by a digestive ferment. 
Several freshly-captured specimensxof Alcyonium digi- 
tatum were examined, but with the exception of the occur- 
rence of afew fragmentary copepods the ccelentera of the 
zooids were invariably empty. Certain feeding operations on 
this form were then attempted, which were at first abortive, 
but finally successful. These experiments were carried out 
in the laboratory of the Biological Station at Port Hrin where 
I was successful in keeping colonies of this species for a con- 
siderable time under healthy conditions. 
1 Corallium rubrum was found to be equally suitable for this purpose, 
and yielded identical results. 
