Dr W. Eutherford on the Fertilisation of Orchids, 71 



out of tliese four species, — self-fertilisation is tmjjossible, — 

 the pollinia must be removed from the flower and applied to 

 the stigma of either the same or another flower. In by far 

 the greater majority of the flowers, the pollinia, where these 

 were single, were both removed, and in only a few of these 

 were the ovaries non-fertilised. Sometimes I found the 

 heads of pollinia sticking to the stigmas : this was rare, how- 

 ever ; more frequently I found bundles broken ofl" from the 

 pollinia adhering to the stigma, and in some of these in- 

 stances the pollinia remained in the same flower untouched, 

 showing conclusively, that these flowers had been fertilised 

 by the pollinia of other flowers. The flowers I examined were 

 generally o?(i, with the viscid discs and stigmas quite dry, so 

 that no farther change could take place in the fertilisation 

 of such flowers. Out of 1304 flowers, 953 had both pollinia 

 removed, of which 895 were fertile and 58 were non-fertile. 

 From this it appears, tliat although the pollinia may have 

 been removed from the flowers, these were sometimes non- 

 fertile. This is, because the insect has carried away the 

 pollinia without pushing them against the stigma, and be- 

 cause the flowers have never been visited by insects having 

 pollinia on their probosces. If such flowers could ever have 

 become fertilised (most were old), it must have been by the 

 pollinia of other flowers. 



In 212, both pollinia were still remaining, although the 

 flowers were mostly dry and shrivelled. Of these 119 were 

 fertile, and 96 were non-fertile, so that although these flowers 

 are incapable of self-fertilisation, the flowers are oftener fer- 

 tilised than not. Insects with pollinia attached to their pro- 

 bosces visited the flowers and fertilised them, although they 

 did not remove the pollinia. Had the flowers grown in a 

 less wooded district, where insects are more scarce, many 

 more of them would have had both pollinia remaining, and 

 fewer of these would have been fertilised. Observe (see the 

 Table at the end) how different is the case of Cejphalanthera 

 grandiflora, which is capable of self-fertilisation, although to 

 a small degree: only 39 out of 1175 flowers had both pollinia 

 remaining, and these, nevertheless, were all fertile; while of 

 the 1128 which had both pollinia removed, only 8 were non- 

 fertile. In the two other species which had the pollinia 



