456 



C. G. MACARTHUR AND E. A. DOISY 



Percentage 

 Increese 

 Per Day 



24- 



?2 



20 



1.3 



1^ 



I.+ 



U 



t.O 



VL 16 20 24 



Time inrnonths 

 Fig. 3 



28 



32 



36 



Protein phosphorus represents the amount of nucleoprotein. 

 This probably closely approximates the changes in the activity 

 of the protoplasm, both nucleus and cytoplasm. This form in- 

 creases in amount with age, but the percentage changes less than 

 any other kind. 



