WATER 



In the untreated normal egg, drop-formation presumably 

 occurs rapidly and the drops are neither so large nor so 

 numerous as in experimental condition. Actually I was 

 able to observe the appearance of drops in normal unfer- 

 tilized eggs. They are much smaller and more evanescent 

 than in the experimentally treated eggs. They appear 

 more clearly in the fertilized than in the unfertilized egg 

 and vary in rate of formation during the cleavage cycle. 

 Drop-formation is thus also in the normal Q^g related to 

 the physiological rhythmical changes coincident with the 

 division-cycle. 



Since these findings indicate that the experimental means 

 merely prolong and render more easily visible the more 

 fleeting changes in the normal eggs, we may with more 

 confidence use the experimental results for interpreting 

 normal conditions and processes. The experiments have 

 far-reaching significance for cell-biology in two respects: 

 they permit conclusions concerning an important aspect 

 of the problem of protoplasmic structure and concerning 

 the question of the movement of water into and out of 

 cells. 



Although we have some information on the struc- 

 ture of protoplasm, we are far from possessing adequate 

 knowledge of it. What is known of the chemistry of 

 the cell does not suffice to tell us whether protoplasm is an 

 emulsion, a suspension, a foam or a combination of these. 

 As said above, an advance is made the moment that the 

 ground substance is recognized as the cytoplasm par excel- 

 lence. This appears as a menstruum containing extremely 

 minute bodies. Since water makes such a large part of 

 protoplasmic structure, we ought to seek to learn how it 

 forms part of this structure: whether it encloses the par- 

 ticles or the particles enclose it; or, in the words of the 

 physical chemist, whether water is in the external or dis- 

 persing or in the internal or dispersed phase. On this 



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