332 SELF-STEKILE PLANTS. CHAP. IX. 



Muller in South Brazil happened to flower a month before 

 any of the others, and it did not produce a single 

 capsule. This led him to make further observations 

 during- the next six generations, and he found that all 

 his plants were completely sterile, unless they were 

 crossed by insects or were artificially fertilised with 

 pollen from a distinct plant, in which case they were 

 completely fertile.* I was much surprised at this fact, 

 as I had found that English plants, when covered by 

 a net, set a considerable number of capsules ;' and that 

 these contained seeds by weight, compared with those 

 on plants intercrossed by the bees, as 71 to 100. 

 Professor Hildebrand, however, found this species 

 much more self-sterile in Germanv than it was with 

 me in England, for the capsules produced by self- 

 fertilised flowers, compared with those from intercrossed 

 flowers, contained seeds in the ratio of only 11 to 100. 

 At my request Fritz Muller sent me from Brazil seeds 

 of his self-sterile plants, from which I raised seedlings. 

 Two of these were covered with a net, and one produced 

 spontaneously only a single capsule containing no good 

 seeds, but yet, when artificially fertilised with its own 

 pollen, produced a few capsules. The other plant pro- 

 duced spontaneously under the net eight capsules, one 

 of which contained no less than thirty seeds, and on 

 an average about ten seeds per capsule. Eight flowers 

 on these two plants were artificially self-fertilised, and 

 produced seven capsules, containing on an average 

 twelve seeds ; eight other flowers were fertilised with 

 pollen from a distinct plant of the Brazilian stock, and 

 produced eight capsules, containing on an average 

 about eighty seeds : this gives a ratio of 15 seeds for 

 the self-fertilised capsules to 100 for the crossed 



* 'Bot. Zeitung,' 1868, p. 115, and 1869, p. 223. 



