THE PHYSIOLOGY OF REGENERATION 123 



maintenance of high rates of glycolysis for up to 6 weeks after 

 section of the body, but these rates fall after that to normal at 10 

 weeks. The five segments in front of the cuts also show an elevation 

 of 68% in glycolytic rates. 



Associated with the accelerated process of glycolysis both lactic 

 acid and pyruvic acid are produced, but only lactic acid increases in 

 concentration, from 10 ju,g/ 100 mg fresh wt. in normal animals to 

 63-5 /ig/100 mg after an anaerobic period in nitrogen. Pyruvic acid 

 falls from 1-7 ju.g/100 mg to 1-0 ^itg/lOO mg. In regenerant tissue the 

 amount of lactic acid is double the normal after 10 days when tissue 

 minces are incubated using glucose as a substrate. 



O'Brien (1957b) thus believes that aerobic metabohsm proceeds 

 through a series of cytochrome-linked enzyme systems in a way 

 similar to that of vertebrates. The initial drop in respiration and 

 aerobic metabolism is due to the sudden loss of enzyme systems and 

 their replacement by the anaerobic glycolytic mechanism, though 

 no decrease was noted in succinoxidase activity. As glycolysis 

 dechnes with the metabolism of glycogen reserves, obtained from 

 body and chloragogen tissue, the aerobic method again takes over, 

 rises to a compensatory peak and later returns to normal. 



Other enzyme changes are described by Powell (1951). Alkaline 

 phosphatase is often found in rapidly metabolizing tissues, and has 

 been described as occurring in the calciferous glands of L. 

 terrestris. It is also normally present in the cytoplasm of the gut 

 epithehum of segments 35-50 but in segments posterior to 55 the 

 enzyme is present only in the cell nuclei. Powell (1951) bisected 

 E.foetida in the region between segments 50 and 5 1 and found that the 

 ATP'ase contents of the five segments immediately anterior to the 

 cuts is greatly reduced. The regenerating segments contain no 

 ATP'ase in the gut. 



This enzyme is also normally found in the ectoderm, and in the 

 tubules and bladder of the nephridia. In regenerating segments the 

 nephridial primordium nuclei show ATP'ase activity which spreads 

 throughout the whole structure as it differentiates into tubules 

 (Powell, 1951). 



The relationship between morphogenetic changes during regener- 

 ation and the metabolic processes involved in tissue reconstitution 

 have received attention from Anderson (see Collier, 1947 ; Anderson, 

 1956). Tubtfex tuhifex was found to respire at a rate of 0-16 ml/g 



