CHORISIS. 345 
** parallel chorisis ;”’ or at right angles to it ‘‘ collateral 
chorisis.”’ 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 
dilamination did really take place ; Dunal and Moquin 
both assert as much. The truth would rather seem to 
be that, im the so-called parallel chorisis at least, the 
process is one of hypertrophy and ovyer-deyelopment 
rather than of splittmg. 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, necessarily, to the so-called 
law of alternation. Out orowths from leaves, multiplymg 
the laminar 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 httle or no doubt that there 
are in reality six stamens in Orchidacee, of which one 
only, under ordinary circumstances, is developed. 
When the numerical symmetry is restored, as it some- 
times is, it 1s obvious that the augmentation that 
_occurs is of a different character from that arising from 
1 On the subject of chorisis or dédoublement the reader may profit- 
ably consult Moguin- Tandon, ‘Ess. sur les Dédoublements,’ and the 
same author in ‘ Ann. Sc. Nat.,’ t. XXVil, p. 236, and ‘ El. ies Veget.,’ 
p. 337. Dunal, ‘Consid. Org. Fleur.,’ Montpell., 1829, p. 32, note 3. 
A. de St. Hilaire i in ‘ Ann. Se. Nat.,’ ser. 3, t. i1, p. 355, ae Lindley, 
‘Elements of Botany,’ p. 76. Asa Gray. ‘Botancal Text Book.’ 
