BIOCHEMICAL STUDIES OF PHYLOGENY 121 



It will not react with creatine since creatine has a CH 3 group 

 substituted for the H on the N marked with a *. However, other 

 compounds such as glycocyamine (this is creatine without the 

 CH 3 group and with an H instead) will give a positive reaction. 



NH 2 



\ 

 HN=C 



/ 

 NH.CH 2 .COOH 



Glycocyamine 



The creatine was determined by the Jaffe reaction, which again 

 is not an absolutely specific test for creatine. 



The arginine from the phosphagen in the echinoderm muscle 

 was thus tested by the Sakaguchi test, by seeing if the muscle 

 extract could synthesise a phosphagen from arginine and phos- 

 phate, and thirdly by adding arginase and seeing if urea was given 

 off. 



The jaw muscles from Sphaer echinus granulans were shown to 

 be capable of synthesising AP (26% of the added phosphoric acid 

 being converted) and CP (12% of the added phosphoric acid 

 being converted). 



Extracts from the longitudinal muscles of Holothuria tubulosa 

 gave extracts that could synthesise AP from A and P (though it 

 should be noted that the Russian workers Verbinskaya, Borsuk 

 and Kreps (1935) found AP and CP in the muscles of the 

 holothurian Cucumaria frondosa). 



Xeedham and Baldwin also quoted work done by P. Baldwin 

 on the ophiuorid Ophioderma longicauda and the crinoid Antedon 

 mediterranea. Ophioderma had CP whilst Antedon had AP. 



The conclusion the authors drew from their work was that the 

 ophiuroids and echinoids and possibly the holothurians had AP 

 and CP and the other echinoderms (asteroids, crinoids) had only 

 AP. 



Let us see to what use this information is put. Hyman (1950) 

 in her text on the echinoderms states on p. 700, " Further bio- 

 chemical evidence supporting the close relationship of echinoids 

 and ophiuroids concerns phosphagens, or phosphorus carriers, of 



