The Pattern of Organic 

 Groivth and Transformation 



'Growth'' is a word of notorious imprecision, but it stoutly 

 defies semantical reform. It may mean increase of length, area, 

 weight or volume; it may mean the act or accomplished fact of 

 reproduction, i.e. increase of number; or it may simply mean 

 development — the adverb is not well chosen — with all that 

 development implies of increasing complexity and elaboration. 

 I shall restrict growth here to its simplest meaning, change of 

 size, but I shall consider also the changes of shape which are 

 the outcome of inequalities in the rate of change of size. 



Organic growth is not a process of accretion, nor does it 

 build upon an enduring frame. The molecular fabric of the 

 body enjoys no substantive permanence whatsoever, a truth 

 which came to be known in the following way. 



The body makes no distinction between the common ele- 

 ments and their various mutants; the natural isotopes of 

 nitrogen and carbon, which have atomic weights of 15 and 13 

 instead of 14 and 12, or the radioactive isotopes of sodium (24) 

 or carbon (14) which arise by gaining neutrons or losing 

 protons, are exchanged indifferently for their common or 

 parental forms. The administration of compounds containing 

 isotopes distinguished by their mass or radioactivity has there- 

 fore made it possible to trace atoms in their passage through 

 the body, and so to reveal the constant exchange of its mole- 

 cular ingredients for new arrivals from the world outside. Even 



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