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 (A sterias forbesii) can be made to develop into larvae by 
any inorganic acid, 1.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. 
1 Loeb, Am. Jour. Physiol., 1V, 423, 1901. 
2 Loeb, Fischer, and Neilson, ‘‘ Weitere Versuche ueber kiinstliche Partheno- 
genese,”’ Pfliiger’s Archiv, LXXXVII, 594, 1901. 
