22 Papers from the Marine Biological Laboratory at Tortugas. 



preamble in mind, the following table will illustrate the effects of the 

 various cations: 



Cation. 



Sodium 



Magnesium. 

 Potassium. . 

 Calcium. . . . 

 Ammonium 

 Hydrogen. . 

 Lithium. . .. 



Effect on 

 neuro-muscu- 

 lar movement. 



-\ 



+ 



Effect on 

 movement 



of cilia 

 of animals. 



- + 



- + 



I am unable to interpret the meaning of this law of the converse 

 effects of cations of blood-salts upon ciliary and upon the neuro-muscular 

 movements of animals, yet any adequate explanation of the phenomena 

 of animal movement must offer an explanation of this relation. Indeed 

 the discovery of this converse relation makes very apparent the incom- 

 pleteness of all existing explanations of the cause of animal movements. 



The electrical stimulation obtained from an induction coil is peculiar 

 in that it excites both the muscles and the cilia. Its effect is to cause the 

 muscles to contract and this contraction stops the cilia in Ctenophores 

 or Veligers, but if the muscles be paralyzed in magnesium so that they 

 can not contract, or if the cilia be not underlaid by muscles, as in the 

 auricles of Bolinopsis vitrea, they are excited when the electrical current 

 passes through them. This leads one to suspect that, whereas a negative 

 variation accompanies neuro-muscular contraction, a positive variation 

 may accompany ciliary excitation, but this hypothesis I have not j'et 

 been able to test experimentally. 



EFFECTS OF lONSiUPON MOTILE PLANT-SPORES. 



It is commonly supposed that ciliary movement is of a very primitive 

 nature, and it naturally occurs to one that the ciliary movements of ani- 

 mals may be a heritage from their more or less plant-like ancestors. If 



this be true we would expect the motile spores 

 of the lower plants to react to electrolytes as do 

 the cilia of animals. I find, however, that there 

 is wide diversity in the behavior of various motile 

 plant-spores under the influence of ions, this 

 being in marked contrast to the uniform reaction 

 of animals, wherein one finds only differences of 

 degree in the behavior of the cilia in forms so 

 diverse as protozoa or spermatozoa, worm larvae, 

 ciliated epithelia of Molluscs, and the combs of 

 Ctenophores. There is, however, a Spirillum 

 which lives .'n a culture of dead house-flies in 

 fresh water which reacts to ions somewhat as do 

 the cilia of animals. This Spirillum is elongate, helically coiled, and of 

 uniform transparency (fig. 8 a) , and it thrives in the water containing 



Fig. 8. — Tv:o soTtsoi Spirillum 

 living in a culture of dead 

 flies in fresh water. 



