Converse Relation between Ciliary and N euro-Muscular Movements. 17 



ceases to pulsate in about 6 minutes, Annelids cease to move in from 

 19 to 70 minutes, and the branchial arms of Lepas can not continue their 

 rhythmical movement for more than 45 minutes. 



Upon Ctenophorse the above solution also causes a momentary 

 cessation of ciliary movement followed by recovery, so that the cilia 

 may continue to beat in a normal rate and manner for more than 9 

 hours. In some cases, however, the cilia, after having recovered their 

 movement, dissolve and disappear in a few minutes a most dramatic 

 occurrence. 



The body-movements of the Ctenophorae cease in about half an 

 hour in this solution. I am inclined to regard the sudden disappearance 

 of the cilia in these Ctenophores as being possibly due to a nervous 

 derangement, for I have seen it occur in Cesium in natural sea -water, 

 the animal suddenly tearing itself into fragments and destroying its 

 entire body without any apparent external cause. 



It is evident that while potassium has but little ability to offset the 

 inhibitory effect of magnesium upon neuro-muscular movements, it 

 exerts a marked influence in sustaining ciliary 

 movements in solutions containing magnesium. 



A solution composed of sodium, magnesium, 

 and calcium chlorides in the amounts and pro- 

 portions of van't Hoff's solution 1 is also effi- 

 cient in sustaining ciliary movement, for in this 

 we find no preliminary checking of ciliary move- 

 ment of the palolo trochophores, and the cilia 

 continue to move for more than 48 hours, the 

 rate continually increasing until it becomes fully 

 that of the normal animal at the end of 24 

 hours, after which it declines. The Spirobran- 

 chus trochophores, however, behave somewhat 

 differently, for their bodies degenerate into mere 

 sacs (fig. 7), and finally, after from 18 to 24 hours, the cilia themselves are 

 gradually absorbed, although still beating until they disappear. In fig. 7, 

 the upper part of the figure shows the normal trochophore of Spiro- 

 branchus ; the lower shows the effect of 18 hours' immersion in a solu- 

 tion containing amounts and proportions of sodium, magnesium, and 

 calcium found in sea-water. 



Those solutions which are most efficient in stimulating ciliary move- 

 ment are the strongest depressants of neuro-muscular activity. For 

 example, neuro-muscular movements cease almost immediately in 0.625 

 molecular MgCl 2 or 0.625 molecular (i2MgCl 2 + 2.5CaC! 2 ) or in 0.625 

 molecular (i2MgCl 2 + 2.5CaCl 2 + 2.2KCl). In the last-named solution the 

 cilia exhibit a momentary pause or a lowering of rate for a few seconds 

 after being placed in the solution, this effect being seen in all solu- 

 tions containing potassium. After this, however, they quickly recover 

 and beat at an abnormally rapid rate but without coordination, each 

 cilium beating independently of its neighbors. This loss of coordination 



1 0.625 molecular (iooNaCl + 

 2 



