120 BIOCHEMICAL STUDIES OF PHYLOGENY 



They concluded, " If any evolutionary significance may be 

 attached to these findings, it is probable that they support the 

 Echinoderm-Enteropneust (Balanoglossus) theory of vertebrate 

 descent rather than any of the other views which from time to 

 time have been put forward on this question." 



In fact the situation was not quite so simple. Thus though the 

 majority of invertebrates have arginine phosphate and the 

 vertebrates have creatine phosphate, the authors found creatine 

 phosphate in the Annelida {Nereis) and in the Mollusca {Sepia) as 

 well as in the echinodermata {Strongylocentrotus) and Proto- 

 chordata {Balanoglossus). In Balanoglossus it was present in only 

 two of the three specimens analysed. 



It would seem that there are no very good grounds for con- 

 cluding from the phosphagen evidence alone that the echinoderms 

 and the protochordates are more closely related to the vertebrates 

 than are, say, the Annelida or the Mollusca. 



In 1936 Baldwin and Needham repeated some of the determina- 

 tions of phosphagens in the echinoderms. There were two 

 problems in which they were interested; the first concerned the 

 formation of the phosphagen. There should be an enzyme present 

 in the tissue that would bring about the phosphorylation of the 

 nitrogenous base and Baldwin and Needham decided to investigate 

 the properties of this enzyme. Secondly they were not sure about 

 the nature of the nitrogenous base in the phosphagen. Though 

 they had felt it might be arginine and/or creatine their tests for 

 these compounds were not specific tests but general ones. Thus 

 the Sakaguchi test for arginine (make the solution alkaline with 

 NaOH; add a little a-naphthol, then add a drop of sodium 

 hypochlorite solution — a bright red colour develops) is not really 

 specific for arginine but is given by the radical marked by a ring. 



NH 2 



\ 



HN=C 



/ 

 Fatty acid group *N-CH 2 .COOH 



CH 3 Creatine 



