52 DYNAMICS OF LIVING MATTER 



decreases quite suddenly. It is obvious that the discontinuity in the 

 curve of duration of life means that here a new condition, or a group 

 of new conditions, enters which before that time were not noticeable. 

 What are these conditions? Experiments which I have recently made 

 on the eggs of sea urchins showed that up to a certain degree the 

 dilution of the sea water with fresh water killed the eggs only slowly, 

 but that beyond a certain degree of dilution death was rather sudden. 

 This sudden death was due to a process of cytolysis in which the eggs 

 were transformed into "shadows." I am inclined to believe that some- 

 thing similar occurs in certain cells of marine Gammarus and of marine 

 animals in general, when the dilution of the sea water falls below a 

 certain limit. 



This idea receives some support from the fact that Wolfgang Ostwald 

 found that a rise in the concentration of the sea water above a certain 

 limit also caused a sudden decline in the vitality curve of fresh-water 

 Gammarus. If the concentration of the sea water be raised above a 

 certain point, the eggs of the sea urchin also undergo cytolysis.* 



* Loeb, Pflugtr's Archiv, Vol. 103, p. 257, 1904. 



