20 



I. LESLIE 



TABLE VI 



Amounts of Ribonucleic Acid Phosphorus (PNA-P) and Deoxyeibonucleic 



Acid Phosphorus (DNA-P) in Rat Liver during the Course of 



Regeneration after Partial Hepatectomy 



Price and Laird^^ and Thomson et al}* find that the DNA-P concentra- 

 tion per unit weight rises to a peak value at the fourth to sixth day after the 

 operation. Since the DNA-P per unit PN also reaches a maximal value at 

 the fourth day, cell size and protein content per cell must be minimal at 

 this stage and must gradually increase during the remainder of regeneration. 

 The rise in PNA-P per unit PN (Table VI, ^^^ ^p ^q ^^g fourth day coincides 

 with rapid cell multiplication, as is also the case in embryonic development 

 (Section IV), and in cultures of Polytomella caeca (Section XI). 



The increase in the size of the remaining kidney which follows unilateral 

 nephrectomy is usually termed "renal hypertrophy." Mandel and his col- 

 laborators find that the increase in kidney size over 80 days is accompanied 

 by a 37 % increase in total DNA-P content and hence, they conclude, a 



