Osmotic Parthenogenesis 63 



Chaetopterus, can be caused to develop by the addition of acid or 

 of any potassium salt to the sea-water without raising its osmotic 

 pressure.' 



Later Neilson and I showed that the unfertilized eggs of the 

 starfish (Asterias forbesii) can be made to develop into larvae by 

 any inorganic acid, i.e., by hydrions. 



In collaboration with Fischer I discovered that the addition 

 of a calcium salt to the sea-water causes the development of the 

 unfertilized eggs of a marine worm, Amphitrite.^ Later on we 

 will return to these investigations. 



'Loeb, Am. Jour: Physiol., IV, 423, 1901. 



2 Loeb, Fischer, and Neilson, " Weitere Versuclie ueber kiiustliche Partlieno- 

 genese," Pfilloer's Arohiv, LrXXXVII, 594, 1901. 



