RESPIRATION 113 



Thus although the Krebs cycle probably does function in 

 oligochaete tissues as in many other organisms, its final acceptance 

 must be tinged with caution until further steps have been 

 elucidated. 



Indications of the course of the energy metaboHsm of earthworms 

 have also been given by a study of the chloragocytes (van Gansen, 

 1958). These cells lying on the coelomic surface of the intestine 

 contain large amounts of glycogen (68-325 /x g/mg wt.), amounting 

 to about 7% of the dry weight of the cell, whilst glucose accounts 

 for a further 3-5% of the dry weight. If the chloragogen cells are 

 washed into a test tube with a saline solution and allowed to stand 

 glycolysis occurs and 60-70% of the initial glycogen content 

 disappears. Glucose- 1 -phosphate appears as an intermediate 

 product in this reaction, but no sign has been seen of glucose-6- 

 phosphate which occurs in vertebrate glycolysis. The enzymatic 

 splitting of glucose- 1 -phosphate has been accomplished using 

 tissue homogenates suggesting the presence of an acid phosphatase, 

 confirmed by histochemical methods (van Gansen, 1958), and a 

 phosphorylase. Experiments designed to give information regarding 

 the aerobic Krebs cycle, however, were not very successful. Tests 

 for dehydrogenase activity using tetrazolium salts and Thunberg 

 techniques were negative for succinic acid, pyruvate, ethanol, 

 malic acid, citric acid and glycerophosphate, all of which are 

 involved directly or indirectly in the glycol3rtic or citric acid cycles. 

 This contrasts with the results of Petrucci (1954) outlined above 

 and further work is required to determine what exactly happens, 

 and to demonstrate the modifications, if any, that occur in different 

 cell types. 



The Energy Store 



During the course of intermediate metabolism much energy is 

 released, amounting to at least thirty-eight high energy phosphate 

 bonds in vertebrates when glucose is metabolized to carbon dioxide 

 and water. These high energy bonds are stored in vertebrates as 

 adenosine triphosphate (ATP) and creatine phosphate (CP). 

 When ATP is reduced to ADP it can again regain a high energy 

 bond from CP via the Lohmann reaction. CP is known as a 

 phosphagen. 



For many years the invertebrate counterpart of CP was thought 



