136 GOOD FEOM CROSSING. Chap. XVII. 



given, but different, inasmuch as individual plants alone of the 

 species are self-impotent. This self-impotence does not depend 

 on the pollen or ovules being in a state unfit for fertilisation, 

 for both have been found effective in union with other plants 

 of the same or of a distinct species. The fact of these plants 

 having spontaneously acquired so peculiar a constitution, that 

 they can be fertilised more readily by the pollen of 



species than by their own, is remarkable. These abnormal 

 cases, as well as the foregoing normal cases, in which certain 

 orchids, for instance, can be much more easily fertilised by the 

 pollen of a distinct species than by their own, are exactly the 

 reverse of what occurs with all ordinary species. For in these 

 latter the two sexual elements of the same individual plant 

 are capable of freely acting on each other; but are so con- 

 stituted that they are more or less impotent when brought into 

 union with the sexual elements of a distinct species, and produce 

 more or less sterile hybrids. It would appear that the pollen 

 or ovules, or both, of the individual plants which are in this 

 abnormal state, have been affected in some strange manner by 

 the conditions to which they themselves or their parents have 

 been exposed ; but whilst thus rendered self-sterile, they have 

 retained the capacity common to most species of partially 

 fertilizing and being partially fertilized by allied forms. How- 

 ever this may be, the subject, to a certain extent, is related 

 to our general conclusion that good is derived from the act < 



crossing 



experimented on two plants of Lobelia fidget 



separate places, and found 64 that their pollen was good, for he fertilised 

 with it L. cardinalis and syphilitica ; their ovules were likewise good, for 

 they were fertilised by the pollen of these same two species ; but these 

 two plants of L. fulgens could not be fertilised by their own pollen, as can 

 generally be effected with perfect ease with this species. Again, the pollen 



:rown 



i»6a 



capable of fertilising V. lychnitis and V. Austriacum ; the ovules could 

 be fertilised by the pollen of V. thapsus ; but the flowers could not be 

 fertilised by their own pollen. Kolreuter, also, 66 gives the case of three 



64 ' Bastarderzeugung, ' s. 64, 357. 65 j& em s . 357, 



66 'Zweite Fortsetzung, ' s. 10; 'Dritte Fort.,' s. 40. ' 



