FOLIAR ORGANS. 355 



tubular, horn-like projections, and in the centre a 

 thread-like process representing the midrib and termi- 



Pio. 185. Supernumei*ary leaf of hazel. 



nated by a small two-lipped limb.^ Dr. Ferdinand 

 Miiller speaks of a leaf of Potiuiderris elHptica as bearing 

 a secondary leaf on its under surface.^ 



The leaves of Heterocentron macrodon have likewise 

 been observed occasionally to produce leaflets from 

 their upper surface. 



To this production of leaves from leaves the late 

 Professor Morren applied the term " autophyllogeny."^ 

 The Belgian botanist figures a small perfect leaf spring- 

 ing from the nerves of the upper surface of the primary 

 leaf in a species of Miconia. As in the hazel, the direc- 

 tion of the adventitious leaf is inversely that of the 

 primary one, the upper surface of the supernumerary 

 leaflet being turned towards the corresponding surface 

 of the normal leaf. A similar occurrence took place 

 in Gesnera zebrinaj but the new growth in this case 

 sprang from the lower face of the leaf. Morren 

 explains the appearances in question by supposing 

 that the supplementary leaf is one of a pair belonging 

 to a bud borne on a slender stalk. This stalk and one^ 

 of the bud-leaves are supposed to be inseparably united 



I ' Bull. Soc, Bot. Fr.,' vol. vii, 1860. p. 587. 



' ' Fragment. Phyt. Austral.,' part xx. p. 270. 



* ' Bull. Acad. Belg.,' xvi, pt. i, p. 60, " Fucbsia," p. 125, c. ic- 



