334 SELF-STERILE PLANTS. CHAP. IX. 



native home of South Brazil, unless fertilised with 

 pollen from a distinct plant, either artificially or 

 naturally by humming-birds.* Several plants were 

 raised from these seeds and kept in the hothouse. 

 They produced flowers very early in the spring, and 

 twenty of them were fertilised, some with pollen from 

 the same flower, and some with pollen from other 

 flowers on the same plants ; but not a single capsule 

 was thus produced, yet the stigmas twenty-seven hours 

 after the application of the pollen were penetrated by 

 the pollen-tubes. At the same time nineteen flowers 

 were crossed with pollen from a distinct plant, and 

 these produced thirteen capsules, all abounding with 

 fine seeds. A greater number of capsules would have 

 been produced by the cross, had not some of the nine- 

 teen flowers been on a plant which was afterwards 

 proved to be from some unknown cause completely 

 sterile with pollen of any kind. Thus far these plants 

 behaved exactly like those in Brazil ; but later in the 

 season, in the latter part of May and in June, they 

 began to produce under a net a few spontaneously 

 self-fertilised capsules. As soon as this occurred, 

 sixteen flowers were fertilised with their own pollen, 

 and these produced five capsules, containing on an 

 average 3*4 seeds. At the same time I selected by 

 chance four capsules from the uncovered plants grow- 

 ing close by, the flowers of which I had seen visited 

 by humble-bees, and these contained on an average 

 21 * 5 seeds ; so that the seeds in the naturally inter- 

 crossed capsules to those in the self-fertilised capsules 

 were as 100 to 16. The interesting point in this case 

 is that these plants, which were unnaturally treated 

 by being grown in pots in a hothouse, under another 



* Jenaische Zeitschr. fur Natiirwiss.' B. vii. 1872, p. 22, and 1873, 

 p. 441. 



