344 PHILOSOPHICAL NOTES ON 



In the apple, pear, and others, the bark ends in the floral 

 leaves. In the orange the bark goes beyond them, and ends by 

 surrounding the ovary, so that it becomes superior. 



This hypothesis would account both for the closeness of the 

 l)eel in certain Citrus, and for its looseness in others, but seemingly 

 would not account for the dissociation of the segments in the 

 tingered citron. But upon further consideration we find that the 

 ordinary leaves, although ex2)ansions of the l)ark, are dissociated 

 from tlie stem-bark, and, therefore, the fingers of this teratological 

 Citrus may be considered as isolated portions of the bark, such as 

 leaves might Ije. 



It will be readily seen that this hypothesis (c) brings us round 

 to hy[)otliesis (b), viz., that the orange-peel is a whorl of a 

 yhyllous nature, and distinct from the enclosed pulp-carpels I 



The solution of this puzzling question seems, then, to rest on 

 another question, viz., whether the bark on the stem receives 

 special fibro- vascular bundles for its nourishment, or is sustained 

 by side branches of the main vessels of the stem. 



According to Sachs' " Phys. of Plants," Figs. 129 and 165, the 

 bark does not receive special vascular bundles. It is cellular in 

 structure, and is in communication with the pith, through the 

 medullary rays. It is only penetrated by the vascular l^undles, 

 which go into each leaf. This is the reason, I imagine, why 

 Van Tieghem, in his transverse sections, shows 0}ily the bundles 

 which go to nourish the pulp-carpels. The peel has no special 

 bundles devoted to it. It is nourished by imbibition from the side 

 branches of the carpel vessels. It and the parenchyma within it 

 correspond to the bark of the stem. 



Indeed, if we examine closely the accompanying Fig. 149, from 

 Payer's *' Traite d'organogenie," we shall soo that tlie pulp-carpels 

 {b) are distinct from the surrounding celhdar tissue {d), which 

 afterwards closes over them and is continued in the style of the 

 pistil. The base (c) of this carpellary cuj) in tlic mature flower 

 becomes the disk^ro/^er (c)j shown in Fig. 150, while an inner 

 disk-whorl becomes connate with the carpels (i), and giows witli 

 them as a coverinr/ bark (the orange peel). AVc see how readily 

 this disk tends to su])-divide itself into projections, both in the 

 Citrus and tlic Jiuta, so that the segments of the fingered citron 

 are not very difl^icult to explain. 



