128 BIOCHEMICAL STUDIES OF PHYLOGENY 



speculation on the occurrence of CP or AP since related genera 

 within a class can differ widely in their phosphagens. The third 

 conclusion is that it is highly probable that other phosphagens in 

 addition to the recently discovered GP and TP will be found to 

 play a role in tissue metabolism. 



Thus Seaman (1952) has isolated a phosphagen from Tetra- 

 hymena gelei that does not appear to be any obvious guanidine 

 derivative, i.e. not arginine, creatine, taurocyamine or glyco- 

 cyamine. Van Thoai and Robin (1954) isolated another phosphagen 

 from the muscles of Lumbricus and called it lombricine. Its 

 structure is shown below. Lombricine has been further analysed 

 by Beatty et al. (1959), who have shown that it contains a d- 

 amino-acid, D-serine. 



NH 2 NH 2 



C = NH O CH— COOH 



I II I 



HN— CH 2 — CH 2 P O— CH 2 



OH 



Lombricine 



Robin, van Thoai and Pradel (1957) described a new guanidine 

 derivative in the leech Hirudo medicinalis but have not as yet 

 published details of its structural formula. 



The function of a scientific theory is to help in our understand- 

 ing of various pieces of information and to suggest further experi- 

 ments that will test the validity of the theory. The value of a 

 theory lies in the extent to which it stimulates the development of 

 such new experiments. The theory concerning the distribution of 

 phosphagens throughout the animal kingdom as suggested by 

 Baldwin and Needham has been a very valuable one when judged 

 in this manner. 



It is becoming clear that the initial impetus that Baldwin, 

 Needham et al. gave to the study of phosphagens has gathered 

 momentum and a great deal of new information has been gathered 

 concerning the chemical nature of phosphagens. What is now 

 required is a very thorough analysis of material from many genera 

 throughout the whole of the invertebrates for information as to 



