STUDIES IN THE PHYSIOLOGY OF 

 FERTILIZATION. 



PART I. ON THE CONDITIONS OF SELF-FERTILIZATION 



IN GIONA. 



By H. M. FUCHS 



(Shuttleworth Student of Gonville and Cwius College, Gamhridge). 



CONTENTS. 



PAGE 



I. Introduction ......... . • 215 



II. Methods; importance of exactness ..... . 221 



III. Factors influencing the extent of self-fertilization ..... 232 



1. Sperm-concentration ......... 232 



2. Length of time that eggs and sperm lie in water before fertilization 234 



3. Position of genital products in their ducts ..... 237 



IV. The effect of a sperm suspension on the eggs of the same individual . . 240 

 v. Comparison of the subsequent development of eggs self- and cross-fertilized 



under various conditions ......... 244 



1. Eggs cross-fertilized at different intervals after the removal of the 



genital products from the body of the animal .... 244 



2. Eggs and sperm from different parts of genital ducts . . . 249 



3. Comparison of development after self- and cross-fertilization . 249 

 VI. Summary of experimental results ........ 253 



VII. Conclusion 254 



Beferences ............. 258 



I. Introduction. 



The main problems presented by the fact of self-sterility — that is 

 to say, the difficulty or impossibility of fertilizing the female gametes 

 of certain hermaphrodite animals and plants with male gametes derived 

 from the same individuals — can be divided under five heads. First, the 

 determination of the degree of self-sterility shown by the individuals 



