X ACKNOWLEDGEMENTS 



I should also like to thank the editors of the following journals 

 for permission to copy and reproduce material. Archive de Zoo- 

 logie General et Experimentale ; Biochemistry, Biophysics Acta; 

 Biochemical Journal; Journal of Bacteriology; Journal of Experi- 

 mental Biology; Proceedings of the Royal Society; Quarterly Review 

 of Biology ; Systematic Zoology and Zoologiska Bidrag. 



