234 HOMOLOGIES OF THE OllAP. VIII. 



lived. Thus the subject of Homology gains largely 

 in interest. 



Although this subject, under whatever aspect it be 

 viewed, will always be most interesting to the student 

 of nature, it is very doubtful whether the following 

 details on the homological nature of the flowers of 

 Orchids will possess any interest for the general reader. 

 If, indeed, he cares to see how much light an acquaint- 

 ance with homology, though far from perfect, throws 

 on a subject, this will, perhaps, be nearly as good an 

 instance as could be given. He will see how curiously 

 a flower may be moulded out of many separate organs, 

 — how perfect the cohesion of primordially distinct 

 parts may become, — how organs may be used for pur- 

 poses widely different from their proper uses, — ^how 

 other organs may be entirely suppressed, or leave mere 

 useless emblems of their former existence. Finally, 

 he will see how enormous has been the amount of 

 change which these flowers have undergone from their 

 parental or typical form. 



Eobert Brown first clearly discussed the homologies 

 of Orchids,* and left, as might be expected, little to 

 be done. Guided by the general structure of mono- 

 cotyledonous plants and by various considerations, 

 he propounded the doctrine that the flower properly 

 consists of three sepals, three petals, six anthers in 

 two whorls or circles (of which only one anther belong- 

 ing to the outer whorl is perfect in all the common 

 forms), and of three pistils, with one of them modified 

 into the rostellum. These fifteen organs are arranged 

 as usual, alternately, three within three, in five whorls. 

 Of the existence of three of the anthers in two of 



* I believe his latest views are the ' Linneau Transactions,' vol. 

 given in Ma celebrated paper, read xvi. p. 685. 

 Nov. 1-15, 18,S1, and published in 



