Role of Salts in Preservation of Life 187 



observation of the eggs of the sea-urchin. If we put the ferti- 

 Hzed eggs of the sea-urchin into an abnormal salt solution, a 

 destruction of the cell gradually takes place. The destruction, 

 as a rule, begins on the surface of the protoplasm, and consists 

 very often in the formation and falling off of small granules or 

 droplets. This process gradually continues from the periphery 

 toward the center until the whole egg is disintegrated. For 

 different salt solutions the picture of the disintegration is a little 

 different, but sufficiently characteristic for a given solution, so 

 that if one become familiar with these pictures, one is able to 

 diagnose to some extent the nature of the solution from the way 

 in which the cell disintegrates. 



This process of disintegration can be observed if the eggs 

 are put into a pure solution of sodium chloride, or in a mixture of 

 sodium chloride and calcium chloride, or in a mixture of sodium 

 chloride and potassium chloride. If, however, all three salts 

 are used in the proportion in which they occur in the sea-water 

 no disintegration takes place and the surface of the egg remains 

 perfectly smooth and normal. One gains the impression as if 

 the protoplasm of the egg were held together by a continuous 

 surface film of a definite texture. If we put the egg into an 

 abnormal solution this surface film is modified and changed, 

 and the change of the surface film is often followed by a gradual 

 process of disintegration of the rest of the cell. 



These observations on the sea-urchin egg, therefore, sug- 

 gest the possibility that the combination of the three salts in 

 their definite proportion and concentration has the function of 

 forming a surface film of a definite structure or texture, 

 around the protoplasm of each cell, by which the protoplasm 

 is kept together, protected against and separated from the 

 surrounding media. 



The previously mentioned observation of Herbst again 

 shows the important role of calcium in this process. 



