WHAT IS PHYSICAL LIFE 



old unicellular things must all depend on 

 the internal organization of its micro- 

 scopic body. There is no way to get round 

 that fact. The whole hereditary past 

 and the whole developmental future, 

 down to its smallest details, are together 

 locked up in that minute speck of living 

 matter. 



The imagination itself refuses to picture 

 at this stage what the internal organization 

 of this wonderful little dot must be, and 

 asks to wait till its subsequent behavior 

 can be observed. Accordingly, the first 

 thing noted about this metazoic cell is that 

 instead of reproducing its like in all par- 

 ticulars as formerly, it divides into two 

 cells, and these then into four, and these 

 into eight, and these again into sixteen, 

 and so on into an indefinite number of 

 divisions. 



But now comes the greatest of all the 

 mysteries of physical life, to which is 

 96 



