338 SELF-STERILE PLANTS. CHAP. IX. 



attracted by the odour, had on some one occasion 

 found an entrance, and had intercrossed a few of the 

 flowers. 



In the spring of 1869 four plants raised from fresh 

 seeds were carefully protected under separate nets; 

 and .now the result was widely different to what it was 

 before. Three of these protected plants became actually 

 loaded with capsules, especially during the early part 

 of the summer ; and this fact indicates that tempera- 

 ture produces some effect, but the experiment given 

 in the following paragraph shows that the innate con- 

 stitution of the plant is a far more important element. 

 The fourth plant produced only a few capsules, many 

 of them of small size ; yet it was far more self-fertile 

 than any of the seven plants tried during the previous 

 year. The flowers on four small branches of this 

 semi-self-sterile plant were smeared with pollen from 

 one of the other plants, and they all produced fine 

 capsules. 



As I was much surprised at the difference in the 

 results of the trials made during the two previous 

 years, six fresh plants were protected by separate nets 

 in the year 1870. Two of these proved almost com- 

 pletely self-sterile, for on carefully searching them I 

 found only three small capsules, each containing either 

 one or two seeds of small size, which, however, ger- 

 minated. A few flowers on both these plants were 

 reciprocally fertilised with each other's pollen, and 

 a few with pollen from one of the following self- 

 fertile plants, and all these flowers produced fine 

 capsules. The four other plants whilst still remaining 

 protected beneath the nets presented a wonderful 

 contrast (though one of them in a somewhat less 

 degree than the others), for they became actually 

 covered with spontaneously self-fertilised capsules, as 



