(Krahl et al. 195U b). It is assumed that each of these substrates is 

 connected to glucose-6-phosphate and that its direct oxidation does not 

 occur, 



Rothschild (19^1) has reviewed the evidence both for Snbden- 

 Meyerhof and hexosemonophosphate paths in eggs of sea urchins. Inac- 

 tivity of the glycolytic pathway in Arbacia eggs also has been suggested 

 by the work of Hutchens et al. (19U2J and Keltch et al. (1901) in which 

 very limited production of lactate following consumption of carbohydrate 

 was shown to occur • Neither the production nor consumption of lactic 

 acid appeared to be important as an energy-yielding process for the first 

 2k hours. Recent work by Krahl (1906) establishes more conclusively the 

 relative importance of the hexosemonophosphate shunt to the firibden- 

 Meyerhof pathway in Arbacia . By determining the ratios of C^UC^ formed 

 by developing eggs and embryos in the presence of the substrates glu- 

 cose-1-Clu, glucose-2-C 1 U, and glucose-6-Clu, he found that glucose 

 appears to oxidize by means of the hexosemonophosphate shunt during 

 the early stages of cleavage, the Qribden-Meyerhof pathway becoming more 

 important during later development. 



Fragmentary information on the carbohydrate metabolism of other 

 aquatic animals is available from studies of a similar nature. ATP- 

 ase activity in heart, skeletal muscle, liver, brain, and kidney tissue 

 of the dolphin also has been exhibited (DuBois et al. 19U8). Marsh 

 (1902) has investigated rigor mortis in the baleen whale in relation 

 to pH, buffering capacity, formation of lactic acid, and dephosphoryl- 

 ation of ATP. In most respects, post-mortem behavior differed little 

 from that of other animals. The high buffering capacity found may be 

 an adaption to extended anaerobic activity. Attempting to estimate 

 the reserves for anaerobic activity in muscle tissue of a variety of 

 animals, Manery (1930) determined the maximum formation of lactic acid 

 that could be produced. Muscle of seal showed no appreciable difference 

 from muscle of cat, dog, rabbit, frog, and tortoise, in this respect. 



That glycolysis proceeds through the Snbden— Meyerhof pathway in 

 various tissues of the dolphin has been shown by DaBois et al. (19U8). 

 Skeletal muscle, brain, liver, kidney, and heart contain the following 

 phosphorylated intermediates of glycolysis: glucose-1-phosphate, glucose- 

 6-phosphate, fructose-6-phosphate, triose phosphate, pentosephosphate, phos- 

 phopyruvic acid, and phosphoglyceric acid. 



A positive assay for a specific enzyme of glycolysis, glycero- 

 phosphate dehydrogenase, has been obtained from isolated frog skin 

 (Hunter and Hunter 19!? 7) • 



The mechanism of ATP-ase activity of lobster muscle has been inves- 

 tigated by Clarke and Koshland (1903). Using H2O 18 , they found that 

 muscle phosphatase hydrolyzes with nucleophilic displacement on the 

 terminal phosphorous atom. 



In summarizing present knowledge of carbohydrate metabolism 

 in aquatic animals, we must say that our knowledge is meager. Since 

 the pathways of glycolysis have been known for many years, however, our 



