358 



REPORT — 1901. 



less radial penetration of the zona pellucida is possibly due to stereotaxis, 

 but a purely mechanical explanation is not excluded. 



Several writers, for instance Wilson,^ and especially Verworn,- have 

 supposed that chemotaxis is a constant factor in the fertilisation of animal 

 eggs. This generalisation, which has been made by arguing from the 

 attraction of spermatozoa to the eggs of certain plants, is as yet entirely 

 without experimental justification as regai'ds animals. From my own 

 results, which agree with those obtained by Massart ^ in the case of the 

 frog, and with the work of Dewitz ^ upon certain insects, I have been led 

 to suppose that whereas contact phenomena are of great importance, 

 chemotaxis, at any rate for a great number of animal species, plays no 

 role whatever in bringing the spermatozoa and eggs into contact. 



Before the close of the year I hope to publish a full account of my 

 work. 



It gives me much pleasure to acknowledge my indebtedness to the 

 Committee of the British Association for the use of the table, and also to 

 the staff at the Stazione Zoologica for their kindness and courtesy. 



APPENDIX II. 



A List of Naturalists who have worked at tlie Zoological Station from 

 the end of June 1900 to the end of June 1901. 



' E. B. Wilson, The Cell in Bevelojjment and Inheritance, 2nd edition, 1900, 

 p. 196. 



- Verworn, Physiologie, 1895, p. 425. 



' Massart, Sidletins de I'Acad. roy. des Sci. de Bclgiqve, 3' ser., torn, xv., No. 5, 

 1888, and torn, xviii., No. 8, 1889. 



* Lfic. cit. 



