302 MULTIPLIGATION. 
CHAPTER IL. 
MULTIPLICATION OF FOLIAR ORGANS. 
Tur cases referrible to this head may be ranged 
under two sections according as the increase is due to 
plurality of ordinarily single organs, or to an increase 
in the number of verticils or whorls. 
When, in place of a single leaf organ two or more 
are really or in appearance present the occurrence may 
be due to one of several causes; among them may be 
mentioned an actual formation of parts in unwonted 
number, hypertrophy or enation, chorisis or fission, 
disjunction, adhesion of one leaf to another or to the 
stem, as in some of the leaves called ‘“ geminate,” 
wherein the two leaves, though ee in juxta- 
position, yet originate from different parts of the stem, 
but by coalescence or lack of separation produce the im- 
pression as if they sprang from the same node. In the 
adult state it 1s not always possible to ascertain with 
certainty to which of these causes the increase in the 
number of leaves is due, though a clue to the real state 
of things may be gained from attention to the distribu- 
tion of the veins, to the arrangement or phyllotaxy of 
the leaves, the size and position of the supernumerary 
organs, &c. 
The term “phyllomania,”’ as ordinarily used, is applied 
to an unwonted development of leafy tissue, as in some 
begonias where the scales or ramenta are replaced by 
small leaflets, or as in some cabbage leaves, from the 
of the sub-division of the leaf-like organs of Sciadopitys verticillata. In 
one instance the pseudo leaf divided, and from the division proceeded a 
little axis, bearing at its summit a verticil of pseudo leaves. This divi- 
sion and formation of new axes and verticils affords ample confirmation 
of the opinion thrown out by Professor Alexander Dickson, that,the 
apparent leaves of this plant were really branches : see ‘ Revue Horti- 
cole,’ 1867, and ‘ Report. Bot. Congress,’ London, 1866, p. 124. 
