6l8 REGENERATION AND GROWTH 7 



up to a late stage (Ryvkina, 1940). It is well known (p. 629) to promote the 

 differentiation of the connective tissues, in association with alkaline phosphatase 

 (Needham, 1952). 



[e) Respiration and caybohydrate-metabohsm 



Recent work has substantiated in general the belief (Needham, 1952) that 

 respiration locally is extensively glycolytic in the R-phase (Table 10) and more 

 fully aerobic again in the P-phase (Table 11). The change probably does not 

 occur until after cell-proliferation, which is favoured by reducing conditions. 

 Antioxidants are extricable from proliferating plant-tissues (Van Fleet, 1954), 

 but pro-oxidants in the later stages of differentiation. The glycolytic phase appears 

 to be no mere accident of disturbed blood-supply since lactic acid, and other prod- 

 ucts of incomplete oxidation, accumulate even in pure oxygen (Ryvkina, 1945). 

 Glycolysis is favourable for proteolysis (Rubel, 1936). Systemically, glycolysis in- 

 creases during the first 12 h. of traumatic shock (Malaguti and Vaccari, 1954; 

 Green and Stonor, 1954), but it seems that here there is an increase in oxygen- 

 consumption from an early stage (p. 610) possibly because glycolytic conditions 

 are intolerable for the healthy tissues of the body. Novikoff and Potter (1948) 

 found little increase in lactic acid, even locally, during liver-regeneration, and 

 more detailed knowledge is required. 



The normal carbohydrates, glucose and glycogen, are no doubt the main sources 

 of energy for regeneration (Weisz, 1948; Novikoff and Potter, 1948; Firket, 1950 

 Frazer, 1953; Jacovleva, 1953; Malaguti and Vaccari, 1954), though Jacovleva 

 (1953), again (Needham, 1952) has found no evidence of extensive use of glycogen 

 during the phase of growth; in vitro, also, there is little evident correlation between 

 growth and carbohydrate-utilisation (Willmer, 1942a). 



On the other hand there is hyperglycaemia and glyconeogenesis in the R-phase 

 (Green and Stonor 1954) which seems as excessive as protein-flow; the latter in- 

 deed may provide carbohydrate by glyconeogenesis, since it is "spared" by ad- 

 ministered carbohydrate (Cuthbertson, et al., 1939). With such large quantities 

 of carbohydrate mobilised systemically, local concentrations may be a false index 

 of local utilisation-rate. Glucose is also the probable source of the amino-sugars and 

 the glucuronic acid of new mucopolysaccharides but for this, again, may be sup- 

 plied systemically and continuously. 



Breakdown products of dedifferentiated mucoproteins (see Kent and White- 

 house, 1955, p. 35) are detected, in the R-phase, both locally (Boas and Foley, 

 1954; Baggi, 1953) and systemically (Schacter et al., 1952). Under the acid con- 

 ditions of the R-phase cathepsins probably initiate the mucolysis (Sherry et al., 

 1954), while fi-glucuronidase catalyses one of the ultimate reactions. Free polysac- 

 charides reach maximal concentration in the blood 24 h. after laparotomy 

 (Schacter et al., 1952), while locally in skin (Boas and Foley, 1954) and bone (Baggi 

 1953) the ultimate degradation-products, glucosamine and galactosamine, are de- 

 tectable. A progressive increase in newly synthesized mucopolysaccharides during 

 the P-phase also has been demonstrated (Sylven, 1941; Balazs and Holmgren, 



1950). 



D-Glucosamine inhibits further mucolysis (Lehmann, 1954a, b) and so when ad- 



