First lUB/IUBS Symposium); Cambridge Philosophical Society 

 for Plate Vlld (from Biological Reviews) ; Cambridge University 

 Press for Fig. 3 (from Ciliary Movement by James Gray) ; Claren- 

 don Press, Oxford, for Plate IXa, b and c (from the Jour7ial of 

 Experimental Botany); The Company of Biologists Ltd. for 

 Figs. 2a and 46 (from the Quarterly Journal of Microscopical 

 Science), Figs. 19, 25, 29, 31, 33, 38, 41a, 41b, 42, 47, 49, 50, the 

 figures in Plate XV and Table 6 (from the Journal of Experimental 

 Biology); The Council of the Marine Biological Association of 

 the United Kingdom for Plates Vlllb, c and IXd, e and Table 8 

 (from the Journal of the Marine Biological Association) ; Macmillan 

 and Co. Ltd. for Fig. 20 (from Nature) ; Nederlandse Vereniging 

 voor Electronenmicroscopie for Fig. 5b (from the Proceedings of 

 the Conference on Electron Microscopy, Delft, 1960); The Northern 

 Association of Obstetricians and Gynaecologists for Fig. 10 

 (from Acta Obstetrica et Gynecologica Scanditiavica) ; The 

 Rockefeller Institute Press for Plates I, II, III, IV, V, Via, b, c, 

 X, XIa, Xllb, Xlir, XI Vc and Figs. 5a, 7, 8, 15 and 17 (from the 

 Journal of Biophysical and Biochemical Cytology); The Royal 

 Entomological Society of London for Plate Xlb (from the Tram- 

 actions of the Royal Entomological Society); The Royal Society 

 for Plates VId and XlVb and Fig. 9 (from the Philosophical 

 Transactions of the Royal Society, Series B) and Figs. 11a, 18 

 and 24 (from the Proceedings of the Royal Society, Series B); 

 Scientific American Inc. for Plate Xlla; the Society of Proto- 

 zoologists for Plate Vila and b and Fig. 14 (from the Journal of 

 Protozoology); The University of Chicago Press for Table 10 

 (from Physiological Zoology); Vaillant Carmanne, Liege, for 

 Plate Vile (from Archives de Biologic); The Wistar Institute 

 of Anatomy and Biology for Fig. 16 (from the Journal of Mor- 

 phology) and Fig. 21 (from the Journal of Cellular and Comparative 

 Physiology) ; Yale University Press for Plate XlVa (from Frontiers 

 in Cytology, Ed. S. L. Palay); The Zoological Society of Japan 

 for Fig. 23 and Table 7 (from Ahnotationes Zoologicae Japu- 

 nenses); The Zoological Society of London for Figs, 34 and 35 

 (from the Proceedings of the Zoological Society of London). 



IX 



