Converse Relation between Ciliary and N euro-Muscular Movements. 5 



and Terry's ^ studies lead to the conjecture that the pulsation of Goni- 

 onemus may possibly be due to an oxidative process within the tissues. 



The calcium of sea-water combines with the sodium ion and assists 

 the sodium to overcome the depressant effect of the magnesium. Cal- 

 cium does not combine directly with magnesium, and in the absence of 

 sodium it has no power to offset the depressant effect of magnesium. 

 I first showed this in 1906, pp. 4, 46, and now present further experimental 

 evidence to the same effect. It is also interesting to see that Joseph and 

 Meltzer, 19 10 (Proc. Soc. Experimental Biology and Medicine, vol. 7, p. 67), 

 find that if the indirect irritability of the muscles of the frog be destroyed 

 by perfusion with magnesium, the irritabihty can not be restored by cal- 

 cium unless sodium be present. 



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

 calcium, and potassium upon the ciHary movements of both marine and 

 fresh-water animals are the exact opposite of their effects upon the 

 neuro-muscular system. Thus for ciliary movement sodium is the most 

 powerful inhibitor, while for the neuro-muscular system it is the most 

 potent stimulant. Similarly, considering the ions magnesium, calcium, 

 and potassium among themselves, magnesium is the most powerful stimu- 

 lant for ciHary movement and the greatest depressant for neuro-muscular 

 movements. Potassium in weak concentrations at first stimulates, but 

 finally depresses the neuro-muscular activities, while it at first depresses 

 and finally permits the movement of ciHa. Calcium depresses neuro- 

 muscular movement, but permits ciHary movement. 



For neuro-muscular activities we find that the stimulating effect of 

 Na is offset by the depressant action of Mg, K, and Ca; whereas in ciHary 

 movements the depressant influence of Na is offset by the stimulation due 

 to Mg, K, and Ca. 



Thus marine invertebrates placed in 0.6 molecular NaCl have their 

 muscular movements most highly accelerated, while their cilia cease to 

 beat almost immediately after immersion in this solution. Also in 0.4 

 molecular MgClj their neuro-muscular movements cease without initial 

 stimulation soon after immersion, while their ciHary movements, although 

 reduced in rate, are maintained for a long time. Ctenophores and 

 ciHated AnneHd larvae illustrate these reactions very clearly. 



R. S. Lillie, 1901-09, in an able series of papers in the American 

 Journal of Physiology,^ found that the muscular movements of marine 

 animals were affected in a manner different from their ciliary movements 

 by the ions Na, Ca, K, and Mg; but he did not observe that the action 

 of these ions upon the neuro-muscular system is in each case the exact 

 opposite of their effect upon ciHa. I find, however, that this law holds 

 not only for the above-mentioned ions of the blood-salts, but also for 

 NH.Cl, which at first stimulates but finally depresses the neuro-muscular 

 movements of animals, while it at first checks and then permits of 

 ciliary movement. Also weak concentrations of acids (hydrogen ion) 

 are momentary stimulants but final depressants for the neuro-muscular 



1 Terry, 1909, American Journal Physiol., vol. 24, pp. 117-123. 



21901, vol. 5, pp. 56-85; 1902, vol. 7, pp. 25-55; 1904, vol. 10, pp. 419- 

 443; 1906, vol. 16, pp. 117-128; 1906, vol. 17, pp. 89-141; 1908, vol. 21, pp. 

 200-220, 1908, vol. 22, pp. 75-90; 1909, vol. 24, pp. 14-44; Ibid., pp. 459-492. 



