THE PHYSIOLOGY OF REGENERATION 121 



proceeds normally. Acetylcholine and the antichohnesterases, 

 parathion and DI syston (0,0-diethyl-5-2(ethylthio)-ethyl- 

 phosphorodithioate) also inhibit regeneration. These observations 

 all indicate the importance of the nervous system in the growth 

 of nev^^ segments, but adrenaline, 5-hydroxytryptamine, atropine, 

 procaine and other substances that also act on the nervous system 

 do not affect the regeneration pattern. It is thus possible that a 

 system linked to the production of acetylcholine may govern 

 regeneration (Massaro and Schrank, 1959). For a further discussion 

 of the part played by the nervous system in regeneration see 

 section on neurosecretion. 



Metabolism in Regeneration 



The metabolic processes involved in the repair of the wound 

 caused by removal of part of the body have been traced in part. 



Liebmann (1942 a, b) postulated that the role of the chloragogen 

 tissue of the coelom was to act as a mobile repair store in case of 

 injury. He showed that eleocytes, chloragogen cells with large 

 basophilic granules, move into a regenerating region of E. foetida 

 from undamaged segments anterior to the wound. At the site of 

 the wound they disintegrate and discharge lipid substances into the 

 region. This process is maximal after 9 hours and then gradually 

 returns to normal during the next 2-3 days. The last trace of the 

 chloragocytes in the regenerant is as a mass of phospholipid 

 granules. The polysaccharide glycogen is also found in large 

 quantities in the chloragocytes and may act as an energy supply to 

 the growing area. Van Gansen (1958) has confirmed the presence of 

 glycogen in the chloragogen cells and this evidence tends to con- 

 firm the bi-functional properties of chloragogen tissue in excre- 

 tion and nutrient storage and mobilization. 



Various metabolic processes in the regeneration of earthworms 

 have been studied by O'Brien (1947, 1957b). Muscle tissue ob- 

 tained from intact Allolobophora respired at an average rate of 

 14-0 /xl 02/hr/lOO mg, varying from 11-4 ^ul 02/hr/lOO mg at the 

 anterior end through 12-7 /xl, 11-9 /Ltl in the mid-regions to 17-2 

 /xl 02/hr/lOO mg at the rear end (last ten segments). Immediately 

 after cutting the rear end away the rate of respiration declines to 

 about 7-0 jul 02/hr/lOO mg. The segments adjacent to the wound 

 continue to exhibit a low oxygen uptake between 7 • 1 and 8 • 5 /xl O 2 /hr / 



