THE BIOLOGY OF THE CELL SURFACE 



mechanical means or by hypotonicity may be interesting 

 and even fascinating and may allow the drawing of some 

 conclusions concerning the normal processes in the living 

 state. However, in the elucidation of the normal processes 

 in the living state, observations and experiments on living 

 eggs whose conditions are only slightly altered, are, as was 

 said in a previous chapter, of higher value for drawing con- 

 clusions than the study of dying or dead eggs. My studies, 

 first made for another purpose, on several species of marine 

 eggs of the rate at which the deleterious effects of hypo- 

 tonic sea-water set in, led me to establish those hypotonic 

 solutions in which the eggs did not break down though 

 they remained in the solutions for hours; indeed, in these 

 solutions these eggs remained intact as long as, or longer 

 than, normal eggs in normal sea-water. We may for our 

 purpose here at once dismiss those grades of hypotonicity 

 which destroy the eggs.^ 



There are grades of hypotonicity which though allowing 

 unfertilized eggs to survive for hours, do in time destroy 

 them, as does normal sea-water which also finally is destruc- 

 tive. Such solutions one must use with caution because 

 what is essential in these studies is the most satisfactory 

 demonstration that the action of the solution can be fully 

 removed — i.e., that eggs after residence in it on return to 

 normal sea-water are as normal as those which never have 

 been in the solution. Usually one measures the size of the 

 unfertilized eggs in sea-water after they are removed from 

 the hypotonic medium; the return to normal size is taken as 

 the criterion that the egg has recovered completely. This, 

 I find, is not enough, I have pointed out that the great 



' It -was deemed necessary clearly to establish in this elaborate 

 fashion that the phenomenon occurred in viable eggs because after 

 the first communication had been given and whenever demonstrations 

 were made, the question, are the eggs ahve? was raised. 



12S 



