J J rof. Vaucher on the Fall of Leaves. 337 



these, the plant is wounded, the fibres lacerated, and the place 

 of junction possesses not the clean and well-defined cicatrix of 

 the leaves which are destined to fall at stated periods. His 

 reflections are — 



1. That the leaves in our climate are nearly all petiolat- 

 ed, never sessile, decurrent, or amplexicaul, and that he 

 knows but of one instance where the stricture is placed in 

 the substance of the leaf, and not at the base of the petiole — 

 the orange. 



2. That leaves are always attached to new stems — never 

 to branches of the preceding year ; and that the necessary 

 union cannot exist between the woody stem and the new 

 leaf. 



3. That the cicatrix which the leaf leaves in falling, and 

 which is well marked in many trees, gradually disappears. 

 The epidermis of the cicatrix is detached, and carries away in 

 falling the last trace of the rupture. 



4. That it is interesting to know whether the peduncles 

 which sustain the fruit, and those which bear flowers and 

 stamens, as in the trees which have catkins, are attached to 

 their places by this predisposed adhesion. These last fall 

 when fecundation is over, while the others adhere till the 

 fruit is mature. Their peduncle acquires a woody consist- 

 ence, and dies a long time before falling. At the period of 

 its fall, occasioned by agitation of the air, it breaks irregu- 

 larly at various parts of its length, and presents, in general, 

 no trace of a ring or stricture. This anomaly affords another 

 proof of that wisdom by which all the processes of Nature are 

 regulated. The male catkins are useless when they have per- 

 formed their office, and of course they fall, but the peduncle 

 of the fruit remains till the fruit reaches maturity. 



5. That there exist many genera of plants, species of which 

 have woody stalks, persistent during winter, while others are 

 annual, or at least only preserved by their roots. Not the 

 least discontinuity is perceived in the petiole of the leaf of the 

 last of those, while in the first, the ring which marks the place 

 of rupture is generally extremely well defined. 



6. The simplicity of the assigned cause is proof of its 

 reality. 



