H. M. FucHS 259 



PART II. THE ACTION OF EGG-SECRETIONS ON THE 

 FERTILIZING POWER OF SPERM. 



CONTENTS. 



PAGE 



I. Introduction 260 



II. Methods 261 



III. Effects of egg- and ovai'y-extracts on fertilization percentages . . . 264 



1. Cross-fertilization of Ciona in egg-extract 264 



2. Cross-fertilization of Ciona in boiled egg-extract .... 266 



3. Cross-fertilization of Ascidia in egg-extract 266 



4. Cross-fertilization of Ciona in ovary-extract ..... 267 



5. Comparison of the effects of egg- and ovary-extracts on fertilization 



in Ciona ........... 268 



6. Comparison of the effects of "foreign" and "own" extracts on 



fertilization in Ciona ......... 268 



IV. Does the extract affect the eggs or the sperm ? 270 



1. Effect of extract on the sperm of Ciona ...... 270 



2. Effect of extract on the eggs of Ciona 272 



3. Effect of extract on the fertilizing power of the sperm of Strongy- 



locentrotus ........... 273 



V. Effects of "egg- waters" on the fertilizing power of sperm .... 276 



1. Experiments with Ciona 277 



2. Experiments with Arbacia ........ 277 



3. Experiments with Strongylocentrotus 278 



VI. Effect of Ciona blood on the fertilizing power of Ciona sperm . . . 279 



VII. Influence of "egg-waters " and egg-extracts of other animals on the fertilizing 



power of Ciona sperm 282 



1. Phallusia egg-extract 282 



2. Arbacia egg-extract 282 



3. Arbacia egg-water 283 



4. Strongylocentrotus egg-extract 284 



5. Strongylocentrotus egg-water 285 



Vin. Further experiments to test the specificity of the egg-secretions . . . 287 



1. Comparison of the effects of Strongylocentrotus and of Ciona egg- 



extracts en the fertilizing power of Strongylocentrotus sperm . 287 



2. Comparison of the effects of Strongylocentrotus and Sphaerechinus 



egg-extracts on the fertilizing power of Strongylocentrotus sperm 288 



3. Comparison of the effects of Strongylocentrotus and Echinus egg- 



extracts on the fertilizing power of Strongylocentrotus sperm . 288 



4. Comparison of the effects of Strongylocentrotus and Echinus egg- 



extracts on the fertilizing power of Echinus sperm . . . 289 



17—2 



