VI 11 



Contents 



CHAPTER VI 



PAGE 



Experimental Hybridizing 66 



Mendel's Law 66 



Mendel's Law and the Germ-cells ..,.,.. 72 



CHAPTER VH 



Experimental Hybridizing (^Continued) 82 



Experiments with Mice ......... 82 



CHAPTER VIII 



Experiments with other Mammals and with Birds 



Experiments with Guinea Pigs 

 Experiments with Rabbits 

 Experiments with Rats 

 Experiments with Cats . 

 Data for Other Mammals and Man 

 Experiments with Poultry 

 Experiments with Pigeons 



99 



99 

 106 

 no 



"3 

 116 

 121 



135 



CHAPTER IX 



Experiments with Snau.s, Moths, and Beetles 139 



Experiments with Silkworms . . . . . . . .141 



Experiments with Beetles . . . . . . , . '^Si 



Experiments with the Currant Moth 153 



Experiments with Tephrosia 153 



CHAPTER X 



Other Kinds of Hybridizing 156 



Blended Inheritance . . .156 



Mosaic Inheritance 157 



Hybridization between Linnaean Species 157 



Dimorphism 160 



Reversal of Symmetry . . . . . . . . . .165 



Conclusions regarding Mendelian Inheritance . . . . . 166 



CHAPTER XI 



Behavior of the Germ-c?:lls in Cross-fertilization . . . .173 



Experiments with Amphibia 173 



Experiments with Echinoderms 175 



Factors involved in the Entrance of the Spermatozoon . . .178 

 Artificial Helps to Fertilization and to Cross-fertilization . . .181 

 Polyspermy 182 



