THE PHYSIOLOGY OF REGENERATION 



125 



Nitrogenous Excretion and Regeneration 



The processes of regeneration must obviously involve great 

 changes in the protein metabolism of the body since these com- 

 pounds provide the structural framevv^ork on which the other 

 cellular constituents can be arranged. No work has yet been 

 published dealing specifically with the protein picture, but 

 Needham (1958) has presented results on the nitrogen excretion 



Days 



Fig. 37. Daily output of ammonia plus amino and urea nitrogen in 

 /LtgN/g wet wt., smoothed by 3-day running averages D — D by 

 anterior halves and Q . • ■ D by posterior halves of fasting Lumbricus 

 prior to and following bisection of the body (from Needham, 

 1958) (by permission of the Wistar Institute). 



pattern of three species of earthworms undergoing regeneration 

 of various fractions of the hind end of the body. The pattern of 

 nitrogenous excretion obviously reflects the protein metabolism 

 of the body. 



Needham finds that the normal basal rate of nitrogen excretion 

 is 142-1 /txg/g/day for L. terrestris, 400 jug/g/day in E. foetida and 

 59-9 /xg/g day in young A. longa in fasting worms. These figures 



