glycogen reserves progressively decline (Hatey lo$i a ,b). Upon injection 

 of glucose, however, the hypopbysectomized eel is able to sySthesize 

 glycogen. In the hypophysectomized, but feeding, fundulus, normal gly- 

 cogen reserves are found (Pickford 1953). 



Glycolysis in the red-colored swim bladder gland of the scup has 

 been demonstrated by Strittmatter et al. (1952). He obtained significant 

 increases in production of lactic acid after addition of glucose and other 

 hexoses to the bisected gland, under both anaerobic and aerobic conditions,, 

 De ymcentus (1952) has measured rates of respiration and glycolysis of 

 retinas of teleosts and of octopuses by manometric measurements, with glu- 

 cose as a substrate. The rate for retinas of octopuses was similar to 

 that found for retinas of teleosts and generally resembled the small values 

 obtained with cold-blooded vertebrates rather than the higher values ob- 

 tained with birds and with mammals. Hishida and Nakano (195H) measured 

 the uptake of glycogen and of oxygen in developing Oryzias eggs. Deter- 

 mination of the respiratory quotient showed that metabolism of carbohy- 

 drate probably begins after the gastrula stagej such a scheme agrees with 

 the glycogen analyses made over this period. Anaerobic glycolysis and 

 lactic acid production also were observed. 



Evidence of glycolysis occurring in the developing fundulus embryo 

 in relation to regulation of osmotic pressure has been shown by Shanklin 

 (195U). That glycolysis supplies the energy necessary for maintaining 

 normal ionic transport and development of the egg was shown by treatment 

 with fluoride and with iodoacetate. These two known glycolytic inhibitors 

 disrupted the normal ionic gradient established across the egg membrane* 

 The enzyme catalyzing the conversion of phosphopyruvate to pyruvate has 

 been shown to occur in the muscle of several species of fish (Boyer 1953) • 

 The presence of adenosine diphosphate (ADP) and potassium ion is essen- 

 tial for the reaction. The presence of this enzyme in all the species 

 tested indicates the probability that other enzymes of the glycolytic 

 system also are present and functioning, 



Hexokinase is a glycolytic enzyme that is responsible for the initial 

 activation of a hexose sugar molecule, thus allowing phosphorylation and 

 the subsequent sequence of intermediary steps of glycolysis to proceed, 

 Kerly and Leaback (195?) found this enzyme to be active in brain homogen- 

 ates of squids ( Sepia officinalis ), elasmobranchs ( Scylli nm canicula and 

 Raia brachyura ), teleosts ( Seophthalmus maximus and Qadus merangulus )^ 

 and frogs ( Rana temporaria )1 Glucose and fructose were utilized at a high 

 rate in all of the species examined, adenosine triphosphate (ATP) being 

 required for activity. The hexokinase of these aquatic animals resembled 

 the nonspecific type found in mammalian brain in that it attacks both al- 

 doses and ketoses and, in contrast to the hexokinase of yeast, is inhibited 

 by its reaction product. 



The hexosemonophosphate shunt is an important oxidative pathway in 

 carbohydrate metabolism. For fertilized eggs of the sea urchin, Arbacia, 



