Relation between Ciliary and Muscular Movements 19 



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The relation between ciliary and muscular movements. 

 By ALFRED G. MAYER. 



[Pet formed at the Marine Laboratory of the Carnegie Institution at 

 Tortugas, Florida.^ 



It appears that in scyphomedusae the nervous stimulus which 

 produces each pulsation is caused by the constant formation of a 

 uric oxalate of sodium in the marginal sense-clubs. This sodium 

 oxalate precipitates the calcium which constantly enters the sense- 

 club from the surrounding sea-water, and forms crystals of calcium 

 oxalate, while sodium chloride is set free. Thus the stimulus 

 which produces pulsation is due to ionic sodium. Pulsation can- 

 not be maintained by the sense organs unless calcium constantly 

 enters them to form the calcium oxalate, and to set free the ionic 

 sodium. 



I find that in annelids, barnacles (Lepas), ctenophores, and 

 medusae, the sodium of the sea-water is a strong neuro-muscular 

 stimulant while the magnesium, calcium and potassium are in- 

 hibitors and exactly counterbalance the stimulating effect of the 

 sodium, thus permitting weak internal stimuli to produce move- 

 ments. 



It is, however, remarkable that the effects of the ions, sodium, 

 magnesium, potassium, and calcium, upon the movements of cilia 

 of infusoria, vertebrate spermatozoa, marine larvae and ctenophores 

 is always the exact opposite of their effect upon the neuro-muscular 

 system. Thus sodium is the most powerful stimulant for the 

 neuro-muscular, and the most potent inhibitor for ciliary move- 

 ment. Similarly considering the ions, magnesium, potassium, and 

 calcium, among themselves, magnesium is most powerful in main- 

 taining ciliary movement, but is the greatest depressant for the 

 neuro-muscular system. Potassium in weak concentration at first 

 stimulates but soon depresses neuro-muscular movements, while 

 conversely it first depresses and then permits ciliary movement. 

 In slightly stronger concentration it at once depresses neuro- 

 muscular, and stimulates ciliary movement. Calcium depresses 

 muscular, but permits of ciliary movement. 



