A Comparative Study of the Phosphagens, with some Remarks on the Origin of Vertebrates

The original discovery of labile phosphorus in muscular tissue by Eggleton and Eggleton (1927, a , b ) was rapidly followed by a succession of researches which demonstrated its great importance in muscular contraction. Fiske and Subbarow (1929) showed shortly afterwards that the phosphagen of the Eggletons was a compound containing equimolecular amounts of creatine and phosphoric acid, which, owing to its great instability in acid solution, had always previously been estimated as inorganic orthophosphate. It remained for the Eggletons (1928), Nachmansohn (1928, 1929, a , b ) and Meyerhof (1930) to delineate the functional importance of phosphagen in the muscle machinery, its breakdown under anaerobic conditions, its restitution in oxygen, and its energetical relations with the lactic acid cycle. In the course of their investigations, Eggleton and Eggleton (1928) examined the tissues of a certain number of invertebrates, and failed to find there any creatine phosphate. About the same time, however, Meyerhof and Lohmann (1928) reported the discovery of another phosphagen in crustacean muscle, a phosphagen in which the creatine portion of the molecule was replaced by arginine. This led to an examination of certain other invertebrates by Meyer­ hof himself (1928), from which a wide distribution of arginine phosphate in the invertebrate Phyla was suggested. Throughout the subsequent discussions it has been assumed that creatine phosphate may be regarded as characteristic of the Vertebrates and arginine phosphate as characteristic of the Invertebrates, although in the absence of thorough-going comparative researches, this view could only remain a very tentative generalisation. “The development of creatine phosphoric acid in the Vertebrates from the arginine phosphoric acid of the Invertebrates,” said Meyerhof (1930, p. 93) “must be regarded as a characteristic chemical mutation.” It is probable that Meyerhof was led to this sharp division by the general conclusions at which Hunter arrives in his monograph on creatine and creatinine (1928). Reviewing the various attempts which have been made to demonstrate the presence of creatine or creatinine in invertebrates ( e . g ., Wilson (1914), Myers (1920)) he points out that nearly all depend on the very unspecific Jaffe reaction, and concludes that up to the present time no good evidence exists in favour of their presence. But this is clearly only a negative conclusion, and the issue is therefore pre­judged when Meyerhof writes, “Corresponding to the restriction of creatine to the vertebrate group, Eggleton and Eggleton failed to find phosphagen in the muscles of invertebrates” (1930, p. 92). Moreover, it is not possible to include all the data in the literature in Hunter’s condemnation, for Quast (1924) in reporting the presence of creatinine in the kidney of the gastropod, Cyclostoma elegans , states that he relied upon the tests of Weyl and Maschke as well as on that of Jaffe. And in any case, there remain large and important groups of animals (the Echinoids for instance) which have never been thoroughly examined either for creatine or for phosphagen.