372 ON CHORlAs. 



to bring under consideration one of the principles which has been pro- 

 posed as a general expression of a number of facts in the structure of 

 flowers, or, as a cause which may be assigned in explanation of some 

 remarkable features belonging to particular flowers, explaining at once 

 the relation to the common plan, and the meaning of the apparent 

 descrepancy in the special case. 



My subject is what was, I believe, first named by the French botan- 

 ist Dunal, chorisis, a Greek word expressing division or separation and 

 applied to supposed cases of a single organ in a floral circle being, so 

 to speak, resolved by subdivision into a number of parts. At present, 

 whilst many high authorities admit this principle as aflFording the true 

 explanation of some remarkable facts in the structure of certain flowers, 

 other authorities of not less general weight entirely reject the principle 

 as unsupported by any sufficient evidence, and not needed to explain 

 the phenomena. In such a case any contribution towards determin- 

 ing the point in dispute may be received with patience and may have 

 some claim to attention. It may be expedient in the first place to con- 

 sider what are the principles in relation to the structure and variation 

 of flowers which may be regarded as known and established, and to 

 what extent they go in explaining the appearances before us that we 

 may be prepared to judge how far further assistance is required, and, 

 if so, how far the proposed principle supplies what is wanted : nor will 

 this view of what may be said to have been accomplished in an im- 

 portant field of enquiry be in itself destitute of utility since compara- 

 tively few years have changed the whole aspect of botanical science, 

 and our greatest practical botanists continue to employ in decsription, 

 terms founded on erroneous opinions, and suggesting false views where 

 on so many accounts the utmost correctness of language is demanded, 

 besides that the truths to be enumerated, though well established and 

 admitted by those esteemed the best judges, are by no means so gene- 

 rally received and applied as not to require to be explained and en- 

 forced. 

 ' The 1st principle to be noticed is that every flower originates in an 

 ordinary bud modified in its development, the increase of the axis 

 being checked and the leaves reduced into circles and made to assume 

 the characteristic forms of floral organs, which setting aside interme- 

 diate and anomalous ones are 4, described and named as follows : the 

 exterior one, usually retaining most of the leafy character called as a 

 ■ whole the calyx, and its separate organs named sepals : within it an- 



