342 



PHILOSOPHICAL NOTES ON' 



It Avould be interesting if some morphologist in India were to 

 investigate the distribution of the vascular bundles of the fingered 

 citrons in the young state of the fruit ; some new light might be 

 thrown on this question. I had not the opportunity of studying 

 them microscopically.* 



In endeavouring recently to work out the genesis of the orange- 

 peel another interpretation has suggested itself, viz. : — 



(<•.) That it is a votttuiuation of the bark, modified as orange- 

 peel. 



I shall try to explain this view l)y means of diagrams. 



In the ordinary branch the bark gives ofE leaves, and goes 

 beyond each leaf or whorl of leaves. In fact, the leaves themselves 

 mav be considered as thin double layers of bark, stiffened and 

 suj)ported bv the fibro-vascular network, which inserts itself 

 between the two l)ark layers. These bark folds are for the purpose 

 of mtdtiplying the surface, and the stiffening is for the purpose of 

 better illumination and aeration. 



O. Penzig (Studj sugli Agrumi, p. 52) tells us that the oil-cells 

 of the upper surface are distinct from those of the lower surface, 

 showing that the leaf consists of two layers of Imrk. In fact, the 

 leaf -nipple, in growing, pushes the bark before it, and ends by 

 becoming enclosed in it, above and below, while the fibro-vascular 

 system of the leaf is developed between the two layers. 



Fig. 146. Diagram showing the bark over the k'af. 



* Mr. ITanbury gro^ s the fingered citron at " La Mortola," on the 

 Riviera. Perliaps somebody may be induced to investigate t^is matter 

 there. 



