140 



GOOD FROM CROSSING. 



Chap. XVII. 



■ 



taken from distinct plants of the same variety, which had, of course been 

 propagated by bulbs, but that they all seeded freely with pollen from 

 any other variety. To give two examples : Ophir did not produce a capsule 

 with its own pollen, but when fertilised with that of Janire, Brenchleyensis 

 Vulcain, and Linne, it produced ten fine capsules ; but the pollen of Ophir 

 was good, for when Linne was fertilised by it seven capsules were 

 produced. This latter variety, on the other hand, was utterly barren with 

 its own pollen, which we have seen was perfectly efficient on Ophir 

 Altogether, Mr. Eawson, in the year 1861, fertilised twenty-six flowers 

 borne by four varieties with pollen taken from other varieties, and every 



single flower produced a fine seed-capsule ; whereas fifty-two flower 



s 



on the same plants, fertilised at the same time with their own pollen 

 did not yield a single seed-capsule. Mr. Eawson fertilised, in some cases 

 the alternate flowers, and in other cases all those down one side of the 

 spike, with pollen of other varieties, and the remaining flowers with their 

 own pollen; I saw these plants when the capsules were nearly mature, 

 and their curious arrangement at once brought full conviction to the 



1m 



r 



hybrids. 



Lastly, I have heard from Dr. E. Bornet, of Antibes, who has made 

 numerous experiments in crossing the species of Cistus, but has not 

 yet published the results, that, when any of these hybrids are fertile, 

 they may be said to be, in regard to function, dioecious ; " for the flowers 

 are always sterile when the pistil is fertilised by pollen taken from the 

 same flower or from flowers on the same plant. But they are often fertile 

 " if pollen be employed from a distinct individual of the same hybrid 

 " nature, or from a hybrid made by a reciprocal cross." 



a 



(( 



Conclusion 



The facts just g 



which show that certain 



plants are self-sterile, although both sexual elements are in a 

 fit state for reproduction when united with distinct individuals 

 of the same or other species, appear at first sight opposed to all 

 analogy. The sexual elements of the same flower have become. 



as already 



ked, differentiated in relation to each 



almost like those of two distinct species 



With 



ipect to the species which, whilst living: under 



natural conditions, have their reproductive organs in this peculiar 

 state, we may conclude that it has been naturally acquired for 

 sake of effectually preventing self-fertilisation. The case is 



closely analogous with dimorphic and 



phic plants, which 



can be fully fertilised only by plants belonging to the opposite 

 form, and not, as in the foregoing cases, indifferently by any 



other plant. Some of 



dimorphic plants are completely 



with pollen taken from the same plant or from the 







