Toxic AND ANTITOXIC EFFECTS OF IONS 711 



added to a sodium-chloride solution, as many eggs develop, 

 and in just as normal a manner, as in ordinary sea-water. 

 The calcium ions in this case undoubtedly serve the purpose 

 of annihilating the poisonous effect of a pure sodium- 

 chloride solution. 



In the meantime I had become familiar with the bril- 

 liant experiments of Hardy upon the influence of ions 

 and the galvanic current upon colloidal solutions. 1 They 

 indicated to me that the next step I had to take was to 

 see whether or not the valency and the sign of the elec- 

 trical charge of an ion determine its physiological effects. 

 I suspected that the antitoxic effect of the calcium ion in 

 the above-mentioned experiment was due to its electrical 

 charge and decided to investigate in a more systematic 

 way whether or not the sign and quantity of the electrical 

 charge influence life-phenomena. My experiments carried 

 on at Woods Hole this summer showed conclusively that 

 this is the case for the antitoxic effects of ions, and prob- 

 ably for the production of rhythmical contractions through 

 ions. It seems at least possible that it is true also for 

 artificial parthenogenesis. 2 



II. THE ANTITOXIC EFFECT OF IONS AS A FUNCTION OF THEIR 

 ELECTRICAL CHARGES AND VALENCY 



1. The development of an embryo from the freshly fer- 

 tilized egg of the before-mentioned fish, Fundulus, served as 

 a test for the toxic and antitoxic effects of ions. I chose 

 this particular animal for two reasons. First, the process of 

 development in this form is to an astonishing degree inde- 

 pendent of the osmotic pressure of the surrounding solution. 

 The egg will develop not only in sea-water, the osmotic 



1 HARDY, Proceedings of the Royal Society, Vol. LXVI (1900). p. 110. 



2 I have not altered this introduction, although I now think it probable that the 

 ions act chemically in all these cases. [1903] 



