6S8 REPORT~1903. 



5. Polymorpldsm in the Pennatulida} 

 By Professor Sydney J. Hickson, F.R.S. 



rennatula Murrai/i was obtained by II.M.S. ' Cliallenfcer ' ofF tlie coast of 

 Ceram, and was first described by Kiilliber. Recently MorofF has described some 

 specimens of the same species from Japanese waters. 



The Dutch Siboga expedition obtained several fine specimens in the Moluccas 

 which have been placed in my hands for examination. 



A characteristic feature of the species, recognised by KoUiker and Moroff, is 

 the presence of a single large siplionozooid at the base of each pinnule, in addition 

 to numerous other siphonozooids of a smaller size on the dorsal and lateral sides 

 of tlie rachis. 



The large siphonozooids can be easily recognised with the naked eye, and are 

 distinguished in well-preserved specimens by their open mouths and by a single 

 pair of papilliform verrucae banging over each of them. 



On further examination the large siphonozooids ai'e found to differ from the 

 ordinary ones in the large size of the stomodteum, the rudimentary condition of 

 the siphonoglyph, and the extraordinary development of the muscles on the lateral 

 mesenteries. 



There can be little doubt that these large siphonozooids are adapted to some 

 special function, and should be regarded as a distinct form or type of zooid in the 

 colonv. Nothing similar to them has hitherto been described in the Pennatulida. 



6. The Assimilation and Distribution of Nutriment in Alcyonlum 

 digitatuni. By Edith M. Pratt, M.Sc. 



When working out the comparative anatomy and histology of several genera 

 of the Alcyonidcp. certain intere.sting features presented themselves in those 



fortions of the zooids which are apparently devoted to the digestive function, 

 was therefore led to a study of the British genus Alcyoniam in the living as 

 well as the preserved condition, and subjected numerous specimens of the species 

 digitatuni to a series of feeding experiment.^ with the view of ascertaining 

 (1) the nature of the food supply, (2) the manner and course of digestion, and 

 (3) the subsequent distribution of nutriment. 



The principal results of these experiments, which were carried out at the 

 Biological Station of Port Erin, may be summarised as follows : — 



1. The Food of Alcyonium. — (a) The zooids of freshly taken colonies of 

 Alcyonium only in rare cases contained food material, which consisted of frag- 

 ments of minute Crustacea, (b) Apparently healthy and hungry colonies refused, 

 with one or two exceptions, to feed on ova of the cod, plaice, whiting, flounder, 

 and extremely small embrj'os of the crab ' Galathea.' (c) When the same colonies 

 were placed in a concentrated tow-netting containing Nauplii, Copepods, and 

 Daphnids, they fed on these small Crustacea wiih great avidity, {d) Similar 

 colonies also readily fed on the pounded flesh of plaice, whiting, and cod. 



From these experiments one would conclude that the coral exercises con- 

 siderable choice in the selection of food material. 



2. Course and Digestion of Food. — By staining the pounded flesh of fish with 

 borax carmine the course of the food could be very easily observed through the 

 transparent body-walls of the expanded zooids. 



The food is captured by the tentacles. If living it is killed by the poisoned 

 threads of the nematocysts, which are extremely numerous on the pinnate ten- 

 tacles. It is then transferred to the mouth by the tentacles and swallowed. In 

 passing through the stomodseum it receives the somewhat scanty secretion from 

 the gland cells lining its walls. It then passes into the ccelenteric cavity, where 

 it is enfolded and squeezed by the ventral and lateral mesenterial filaments, which 

 also pour on to the food a copious secretion from their gland cells, which are 



' Will be published in extenso in the Reports of the Siboga expedition. 



