" parallel cliorisis ;" or at right angles to it " collateral 

 cborisis." Indeed, before so much attention had been 

 paid to the way in which the floral organs are deve- 

 loped, it was thought that an actual splitting and 

 dilamiiiation did really take place ; Dunal and Moquin 

 both assert as much. The truth would rather seem to 

 be that, in the so-called parallel chorisis at least, the 

 process is one of hypertrophy and over-development 

 rather than of splitting. The adventitious petal or 

 scale is an excrescence or an outgrowth from the pri- 

 mary organ, and formed subsequently to it. 



In the case of " compound stamens" the original 

 stamens are first developed each from its own cellular 

 " mamelon," or growing point ; and, after a time, other 

 secondary growing points emerge from the primary 

 one, and in this way the stamens are increased in 

 number, without reference, necessai'ily, to the so-called 

 law of alternation. Outgrowths from leaves, multiplying 

 .the laminaf surface, are alluded to under the head of 

 hypertrophy, and it is probable that some of the cases 

 of duplication of the flower, or of the formation of 

 adventitious segments outside the ordinary corolla as 

 alluded to in succeeding paragraphs (see Pleiotaxy of 

 the corolla), are due to a similar process.^ 



The formation of parts in unwonted numbers may 

 be merely a reversion to what is supposed to have been 

 the original form, and in this way there may be a 

 restoration of parts that are usually undeveloped or 

 suppressed. There can be little or no doubt that there 

 are in reahty six stamens in Orchidacece, of which one 

 only, under ordinary circumstances, is developed. 

 When the numerical symmetry is restored, as it some- 

 times is, it is obvious that the augmentation that 

 occurs is of a different character from that arising from 



' On the subject of cliorisis or dedoublement the reader may profit- 

 ably consult Moquin-Tandon, ' Ess. sur les Dedoublenients,' and the 

 same author in ' Ann. Sc. Nat.,' t. xxvii, p. 236, and ' El. Ter. Veget,,' 

 p. 337. Dunal, ' Consid. Org. Flour.,' Montpell., 1829, p. 32, note 3. 

 A. de St. Hilaire in ' Ann. Sc. Nat.,' ser. 3, t. iii, p. 355, adnot. Lindley, 

 ' Elements of Botany,' p. 76. Asa Gray, ' Botanical Text Book.' 



