f £.' LIBRARY ! 



iNTS 



Preface vii 



Acknowledgements ix 



1 INTRODUCTION 1 



2 BASIC ASSUMPTIONS 6 



3 VIRUSES, RICKETTSIAE AND BACTERIA 18 



4 THE PROTOZOA 26 



5 ORIGIN OF THE METAZOA 36 



6 THE MOST PRIMITIVE METAZOA 50 



(1) PORIFERA 54 



(2) MESOZOA 71 



(3) COELENTERATA 76 



(4) CTENOPHORA 84 



(5) PLATYHELMINTHES 94 



7 THE INVERTEBRATE PHYLA 101 



8 BIOCHEMICAL STUDIES OF PHYLOGENY 112 



(1) PHOSPHAGENS 112 



(2) STEROLS 129 



9 VERTEBRATE PALAEONTOLOGY 134 

 10 CONCLUSIONS 150 



