Unisexual Crosses 257 



do not possess, and for this reason afford a 

 pure instance of unisexual union, thougli differ- 

 ing in more than one point. 



I have made reciprocal crosses, taking at one 

 time the small-flowered and at the other the 

 common species as pistillate parent. These 

 crosses do not lead to the same hybrid as is 

 often supposed in analogous cases ; quite on the 

 contrary, the two types are different in most 

 features, both resembling the pollen-parent 

 far more than the pistil-parent. The same 

 curious result was reached in sundry other re- 

 ciprocal crosses between species of this genus. 

 But I will limit myself here to one of the two 

 hybrids. 



In the summer of 1895 I castrated some flow- 

 ers of 0. muricata, and pollinated them with 0. 

 biennis, surrounding the flowers with paper 

 bags so as to exclude the visits of insects. I 

 sowed the seeds in 1896 and the hybrids were 

 biennial and flowered abundantly the next year 

 and were artificially fertilized with their own 

 pollen, but gave only a very small harvest. 

 Many capsules failed, and the remaining con- 

 tained only some few ripe seeds. 



From these I had in the following year the 

 second hybrid generation, and in the same way 

 I cultivated also the third and fourth. These 

 were as imperfectly fertile as the first, and in 



