122 THE PHYSIOLOGY OF EARTHWORMS 



100 mg, but the regenerating tissue rises from 7-0 to 1 1 -4 ^tl 02/hr/ 

 100 mg wet weight after one week (O'Brien, 1947). 



The average endogenous respiration rate of minced muscle tissue 

 from E.foetida is about 30 lA. O2/IOO mg wet wt./hr, considerably 

 higher than that of Allolobophora. When E. foetida was sectioned 

 at segments 60/61 the respiratory rate fell sharply to about 

 10 /xl O2/IOO mg wet wt./hr, but this was followed by a rise to a 

 maximum of about 40 ix\ O2/IOO mg wet wt./hr, after approximately 

 3 wrecks. From this time on values declined slowly towards normal at 

 10 weeks. The high respiration rates are correlated with a rapid 

 growth rate, the regenerants adding thirty-three segments in the 

 first 4 weeks, but only a further seven segments thereafter (O'Brien, 

 1957b). Enzyme activity in the form of succinoxidase does not 

 show an early decrease but otherwise parallels the respiratorv 

 changes. During the early fast-respiring period of regenerate 

 growth, particularly days 8-12, the blastema increases rapidly in 

 size and differentiation of tissues goes on. It is a time when con- 

 siderable increase in nucleic acids, especially RNA, occurs and it 

 is found that barbituric acid effectively inhibits regeneration. This 

 substance is thought to suppress nucleic acid synthesis (Massaro 

 and Schrank, 1959). 



Glycogen is present as 5-0 mg/g body weight in normally feeding 

 animals, declining slowly upon starvation to about 3-0 mg/g body 

 weight after 6 weeks. Y^htnE. foetida is bisected the glycogen content 

 of the area very quickly falls to 2-1 mg/g in the five segments next 

 to the wound. The preceding ten segments also have glycogen 

 content below the normal figure. When the first small regenerant 

 appears it has a glycogen content of only 0-2 mg/g wet wt. and it 

 remains at a low level until regeneration is complete after 10 weeks. 

 This suggests that glycogen is metabolized as fast as it is synthe- 

 sized, preventing the build-up of stored glycogen until the growing 

 phase is over. Glycolysis in the regenerant (10 days) proceeds at a 

 rate 80% higher than that of normal uninjured tissues (O'Brien, 

 1957b) and the inhibition of glyceraldehyde dehydrogenase by 

 iodoacetic acid (lAA) interferes with glycolysis and depresses 

 regenerant growth. Little effect is noted initially, but inhibition of 

 segments gradually increases up to 24 days treatment after injury 

 (Massaro and Schrank, 1959). 



This gradually increasing effect of lAA is paralleled by the 



