314 Mr Gray, The Effect of Ions on Ciliary Motion 



buffer such as sodium bicarbonate. In the case of the salts of the 

 alkaline earths it is impossible to obtain pure isotonic solution of 

 the same hydrogen ion concentration as sea-water, and it is there- 

 fore necessary to compare the effects of the pure solutions with 

 that of sea-water whose hydrogen ion concentration is abnormally 

 high. 



A number of experiments have been performed which prove 

 that sodium, potassium, calcium and magnesium are all necessary 

 to maintain gill fragments in a normal state of ciliary activity 

 for a protracted period, viz. four days. If one or more metals are 

 omitted, the individual cells of the ciliated epithelia show the same 

 disruptive phenomenon as in sea-water of abnormally high con- 

 centration of hydroxyl ions. Solutions containing only one metal 

 show this phenomenon to a very marked degree although they 

 may be more acid than normal sea-water; the effect of solutions 

 containing two metals is less marked than that of solutions contain- 

 ing only one metal, but more marked than that of solutions con- 

 taining three metals. No evidence was obtained of specific ion 

 action or of antagonistic action between monovalent and divalent 

 ions. 



These experiments afford another example of the intense action 

 of the hydrogen ion upon physiological activity and of its reversible 

 nature if the acid treatment is not too severe. The same action of 

 acids is found in the activity of the heart and in the movement of 

 spermatozoa. 



