78 GENERAL REVIEW OF THE ORCHIDE.E. ! 



Of the known causes that occasion self fertiUsation Mr. Ridley describes i 

 four of the commonest. 1, by the breaking up of the pollen masses . 

 and the falling of the dust either directly upon the stigma or into the > 

 lip, whence it comes into contact with the stigma. This can happen | 

 only in the case of orchids with pulverulent pollen as in Cypripedium ' 

 Schlimii and the terrestrial kinds as Ophrys, lieottia, Thelymitra, etc. 

 2, by the falling of the pollen masses as a whole from the clinandrium ^ 

 into the stigma. This happens in the case of Phaius grandifolius 

 Bernaysii and probably others. 3, by the falling forward of the poUinia 

 from the clinandrium or anther cap, the caudicle and gland remaining 

 attached to the column. Our native Bee Orchis, Ophrys aplfera, is 

 a well-known instance of this. 4, by the flooding of the stigma. The 

 pollen masses remain in the anther cap while the stigma exudes so 

 great a quantity of stigmatic fluid that it eventually reaches the edge i 

 of the pollinia which immediately emit pollen tubes. This is the case 

 with Ghysis aurea, Lcdia virens, Dendrohium aqueum and probably others 

 mentioned above ; it seems to be the commonest method of self-fertilisation. 



We cannot conclude our notes on the self-fertilising of orchids 

 more appropriately than by quoting Mr. Darwin's own words. 



" Considering how precious the pollen of orchids evidently is and 

 what care has been bestowed on its organisation and on the accessory 

 parts ; considering that the anther always stands close behind or above 

 the stigma, self -fertilisation would have been an incomparably safer 

 process than the transportal of the pollen from flower to flower. It 

 is an astonishing fact that self-fertilisation should not have been an 

 habitual occurrence. It apparently demonstrates to us that there must 

 be something injurious in the process. Nature thus tells us in the 

 most emphatic manner that she abhors perpetual self-fertilisation." * 



Reverting again to the manifold and wonderful contrivances to be 

 found in orchid flowers which subserve their fertilisation, we have 

 in the Synopses of the Genera and Species occasionally noted 

 peculiar structures which could have been designed for no other 

 end.t From the many instances so lucidly described by Mr. Darwin 

 we select one, Dendrohium chrysanthnui, which, as he has pointed 

 out, is interesting from being apparently contrived to effect its own 

 fertilisation if an insect should accidentally fail to remove the pollen 

 masses. By the kindness of the proprietors and publishers of 

 Fertilisation of Orchids we are enabled to i-eproduce the original figure 

 of this species showing how this is effected. 



'' Fertilisation of Orchids, p. 359. 

 t Corycmlhcs macrantha, p. 106 ; Oncidium hians, p. 44 ; also Stauhopea, Monnodes, etc. 



