124 BIOCHEMICAL STUDIES OF PHYLOGENY 



Baldwin and Yudkin (1949) also carried out some analyses of 

 the phosphagens in echinoderms and protochordates. They con- 

 cluded that the hemichordates and the echinoids were unique in 

 that they both had CP and AP whilst the other echinoderms 

 (except for ophiuroids) had only AP. These results were presented 

 in tabular form and indicated that the vertebrates were derived 

 from the Echinoderm-Protochordate line. 



In fact the evidence for the phylogenetic value of phosphagens 

 is not very good. Out of the three hemichordates studied, 

 Balanoglossus salmoneus, Saccoglossus kowalezvsky and Saccoglossus 

 horsti, only the former has AP whilst the others have CP. Rees 

 (1958) states that in his analysis of twenty specimens of Balano- 

 glossus clavigerus he was able to find only CP; there was no 

 indication of AP. 



Amongst the echinoids the jaw muscles of Arbacia punctulata 

 have only AP and no CP whilst Strongylocentrotus lividus and 

 Echinus esculentus have both CP and AP. Similarly Griffiths, 

 Morrison and Ennor (1957) showed that though some echinoids 

 such as Heliocidaris erythrogramma had both CP and AP, others 

 such as Centrostephanus rodgersi had AP and no CP. These 

 authors concluded, " The general assumption of Baldwin and 

 Needham that both AP and CP are found in the echinoids is thus 

 disproved and the results emphasise the necessity for examining a 

 number of species within a class before concluding that a particular 

 phosphagen is characteristic of the class." If one was to take the 

 possession of the phosphagens as a serious phylogenetic feature 

 one might conclude that since the ophiuroids have only CP like 

 the vertebrates that they in fact are the closest of the echinoderms 

 to the vertebrates. 



The phosphagen story took a new turn in the 1950s when 

 chromatographic analysis was applied to the guanidine com- 

 pounds. As we have already seen, the previous workers were only 

 concerned with two guanidines, creatine and arginine, and they 

 differentiated these on the rate of hydrolysis and various non- 

 specific tests. French workers at the Laboratory of Comparative 

 Biochemistry of the College de France (van Thoai, Roche, Robin 

 and Thiem, 1953) showed that the annelids contained at least two 

 other phosphagens. They found these by running ascending 



