GENERAL REVIEW OP THE ORC'HlDE/1';. 



all tlu'cc are fertile.* Althoiigli in no true orchid except those mentioned 

 are the t\vo anthers of the inner whorl fully developed, their rudiments 

 are generally present and are often utilised ; for they generally form 

 the membraneous sides of the cliuandrium or cup on the summit of 

 the column which includes and protects the pollen masses ; these 

 rudiments thus aid their fertile brother anther, f But more recent and 

 exhaus*^ive investigations of the anatomy of the column of orchids 

 undertaken by M. Philippe Van Tieghem, the results of which are 

 published in vol. XXI. of the Mt' moires of the French Institute, prove 

 conclusively that Mr. Darwin's view of the stamens concealed in the 

 labelhini must be modified. M, Van Tieghem has shown that the 

 rudiments of the stamens marked A2, A3 are situated not in the 

 labellum but in the column like those of the inner whorl. The circles 

 Al', A'.') in the diagram indicate only branches of the fibro-vascular 

 bundle entering the labellum. 



Such is the view of the ancestral type or general pattern of an 

 orchid flower entertained by one of the most profound naturalists of 

 our time, and as modified by INI. Van Tieghem's researches, generally 

 acce[)ted by men of science. No single species now exists exhibiting 

 this full pattern, nor can we be sure that any such jiattern ever did 

 exist ; but this in no wise weakens the foundation on which the 

 hypothesis rests, nor do the comparatively few exceptional cases in 

 which the course of the fibro-vascular bundles are found to deviate 

 from the general plan, as in the great genus Habenaria. The strength 

 of the hypothesis of this ideal type rests on its competence to 

 account for in the most conclusive manner the general structure of 

 all the orchid flowers we see, notwithstanding the endless variety 

 (if forms into which they have been moulded. We conclude our 

 notice of this most interesting subject in Mr. Darwin's own words. 



" It is interesting to look at one ol the magnificent exotic species, 

 or ind('ed at one of our humblest forms, and observe' how profoundly 

 it has Ijecn modified as compared Avith all ordinary flowers — with its 

 usually great labellum taking the place of one petal — with its singular 

 jjollen masses — with its column formed of seven (nine) cohering organs, 

 of which three alone })erform their proper functions, namely, one anther 

 and two generally confluent stigmas — with the third stigma incapable of 

 fertilisation and modified into the wonderful rostellum — with three 

 (five) of the anthers no longer capable of producing pollen, but serving 

 either to protect the pollen of the fertile anther, or to strengthen the 

 column, or existing as mere rudiments, or entirely suppressed, What 

 an amount of niodification, change of function, cohesion and abortion 

 do we here see ! 



" The genus Neuwiedia is the nearest approacli to the ancestral form at present known, 

 t Fertilisation of Orchids, p. 298. 



