24 Coelenterata. 



feeble development of nematocysts (as in the Protanthese). The cilia of the 

 tentacles strike towards the tip, those of the oral disc from its centre to its 

 periphery, those of the stomodseum either inwards or outwards according to 

 physiological conditions (but in H. only the outward stroke has been observed). 

 In Caryophyllia cyathus, along with the formation of stronger batteries of 

 nematocysts, the cilia of the tentacles have disappeared but cilia persist on the 

 column-wall (beating towards the pedal disc), stomodseum (beating inwards) and 

 oral disc; those of the inner part of the oral disc beat inwards, those of the 

 outer part outwards. The reduction of the ectodermal cilia is greatest in those 

 species with strong nematocysts in their tentacles, e. g. Tealia coriacea, Actinostola 

 callosa and Bolocera longicornis, in which cilia persist only on the oral disc 

 and beat inwards or outwards according to physiological conditions. When 

 a siphonoglyph or two are present (there is none in Protanthese, H. and C.) 

 they are always ciliated and the cilia always beat inwards thus causing a 

 current of fresh water into the coelenteron. All the ectodermal cilia of 

 Protanthese beat so as to carry food particles into the ccelenteron (the cilia 

 of the tentacles only when the latter are bent over the mouth); similarly in 

 G. except in regard to the cilia of the proximal part of the column-wall [see 

 above]. In H., M. and S. food particles are carried to the interior by means 

 of the cilia of the tentacles and stomodseum, those of the oral disc being of 

 little or no use in the transport of food. In C. the cilia of the inner part 

 of the oral disc and of the stomodseum strike inwards carrying food to the 

 interior, those of the outer part of the oral disc and of the column-wall serve 

 to carry away waste particles expelled from the mouth, and, in the contracted 

 animal, serve to keep the parts free from detritus. In T 7 ., B. and A. the cilia 

 play only a feeble part in carrying food inwards, the stomodseal cilia aid in 

 expelling waste particles. In Protanthese ciliary action is chiefly responsible 

 for the intaking of food. In M. and S. when a food particle touches a tentacle 

 the latter contracts (according to the strength of the stimulus, the neighbouring 

 or all the tentacles may be affected) and bends towards the mouth, the food 

 particle is carried by the action of the tentacular cilia to the mouth and then 

 by the stomodseal cilia, and to a less extent by peristalsis, into the coelenteron. 

 In C. food particles were captured by one or more tentacles which contracted, 

 bent towards the mouth and transferred the particles to the inner part of the 

 oral disc or to the mouth whence by action of the cilia of the oral disc and 

 stomodseum they were carried into the coelenteron. If the pieces were larger 

 the peristaltic action of the stomodseum aided their ingestion. In T 7 ., A. and 

 B. the food was captured by the tentacles and transferred to the edge of the 

 mouth whence, chiefly by peristalsis, and to a less extent by ciliary action, 

 it was carried to the inner end of the stomodseum. In M. and S. by means 

 of the cilia of the stomodseum, oral disc and tentacles, waste particles 

 are carried from the coelenteron to the tips of the extended tentacles. In C. 

 waste particles are brought up from the aboral part of the coelenteron to the 

 inner end of the stomodseum by means of the mesenterial filaments, thence 

 they are expelled, along with a stream of water, by strong contraction of the 

 body. In case such particles fall again upon the animal they are carried, by 

 means of the cilia of the outer part of the oral disc and of the column-wall, 

 to the pedal region. In T. and A. small waste particles are swept out by 

 the cilia of the stomodseum on to the oral disc and are then removed by 

 contractions of the body, larger masses are expelled, along with a current of 

 water, by contraction of the animal, possibly peristalsis of the stomodseum 

 also assists. 



