Toxto AND ANTITOXIC EFFrcts or Ions’ T11 
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.' 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.” 
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 Harpy, Proceedings of the Royal Society, Vol. LXVI (1900), p. 110. 
2T have not altered this introduction, although I now think it probable that the 
ions act chemically in all these cases. [1903] 
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