TYPES OF NEUROMUSCULAR MECHANISM IN SEA- 

 ANEMONES., 



By G. H. PARKER, S.D. 



(Read April 15, igi6.) 



Sea-anemones possess at least four systems of organs by which 

 they react to environmental changes : the glandular system, especially 

 the mucous glands, the ciliary system, the nematocyst system, and 

 the muscular system. Of these the first three are strictly local in 

 their responses in that they become active only in the exact regions 

 where they are stimulated. Moreover they remain normally re- 

 sponsive in animals that have been so completely anesthetized with 

 magnesium sulphate or chloretone as to exhibit no nervous activity. 

 Hence there is good reason to assume, notwithstanding the opinion 

 held by some of the older workers, that none of these three systems 

 are under nervous influence. The fourth system, the muscular, is 

 well known to be controlled by the nervous system of these animals. 

 In the common New England sea-anemone, Metridhirn marginatum, 

 the neuromuscular mechanism includes at least thirteen muscles or 

 groups of muscles. Two of these are ectodermic, (i) the longi- 

 tudinal muscle of the tentacles and (2) the radial muscle of the 

 oral disc; the remaining eleven are entodermic and are as follows: 

 (3) the circular muscle of the tentacles, (4) the circular muscle of 

 the oral disc, (5) the circular muscle of the oesophagus, (6) the 

 sphincter, (7) the circular muscle of the column, (8) the circular 

 muscle of the pedal disc, and the five mesenteric muscles, namely, 

 (9) the basilar muscles, (10) the longitudinal mesenteric muscles, 

 (11) the transverse mesenteric muscles, (12) the parietal muscles, 

 and (13) the longitudinal muscles of the acontia or nettling 

 filaments. 



The nervous mechanism by which these muscles have long been 

 supposed to be brought into action is a network of neurofibrils and 

 the like which permeates the deeper regions of the ectoderm and the 



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