THE BIOLOGY OF THE CELL SURFACE 



of experimental embryology as a punitive expedition against 

 the egg, let us hope, have passed. Instead comes the time 

 of nice, exact, carefully graded treatment, wherever possible 

 reversible in its action, for the purpose of analyzing develop- 

 ment in ever more closely set stages, after this has been 

 mapped out in the perfectly normal egg with meticulous 

 care and scrupulous cleanliness. The most minute space- 

 time organization of the living system makes the instrument 

 on whose strings play the processes by action and inter- 

 action. By experiment we here slightly exaggerate, there 

 lightly fret the tones out of which the harmony of the 

 living state arises. 



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