142 



BROOKLYN BOTANIC GARDEN MEMOIRS 



wholly self-sterile the second season, when grown in Brazil. One 

 may assume, I think, arguing from data of similar character, that this 

 progressive result was not due to actual inheritance of an acquired 

 character but rather to the fact that the first generation in each case 

 passed a portion of its life cycle in the original environment. 



Similar results were obtained in the case of Abutilon darwinii, 

 which though self-sterile in its native Brazil, became moderately self- 

 fertile late in the first flowering season in Darwin\s greenhouse. 



Darwin made more detailed experiments on Senecio cruentus, 

 Reseda odorata and Reseda lutea and found, as he believed, that each 

 plant though self-sterile was cross-fertile with every other plant. 

 His pollination experiments with Senecio cruentus and Reseda lutea 

 were so inadequate that they may be omitted from consideration; it 

 was really his experiments on Reseda odorata that were thought to 

 establish the fact of complete cross-fertility. 



Darwin's Experiments on Reseda odorata in 1868 

 Male Parents 

 A B C D E F G 



Only sixteen cross matings were made, however, and this is not 

 sufficient to prove the point, as is shown by one of our own experi- 

 ments, where 131 cross-matings were made with only 4 cases of cross- 

 sterility. From the fertile cross-pollinations Darwin raised four 

 plants in 1869. Three of these proved to be self-fertile and one self- 

 sterile. Six more plants were grown in 1870. Of these, two were 

 almost self-sterile and four were almost completely self-fertile. The 

 former produced altogether five seeds from self-pollinations, and the 

 resulting plants proved to be self-sterile like their parents. These 

 varied results Darwin attributed to a difTerence in inherited sexual 

 constitution, but it seems to me that this conclusion should be ques- 

 tioned. Our own resu Its have proved conclusively that toward the 



