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The Museum Gazette 



it is produced can hardly be termed a true joint, for certain 

 structures run in unbroken continuity from the stem to the 

 appendage. These are the fibro- vascular bundles by which 

 the appendage is fed and also fixed in place. These bundles 

 are usually quite visible in the scar-surface left when a leaf or 

 fruit is broken off. They are " the nails in the horse-shoe " of 

 the leaf-scar of the horse chestnut. Still, it is certain that a 

 sort of joint is present, and that the structures are continuous 

 in a very different sense from that of a stem or true branch. 

 You may observe this difference in my acorn-bearing twig, for 

 there are two acorn cups, and one has been produced by a 

 branching out from the stem of the other. This little branch 

 is smoothly continuous with the parent branch, and shows no 

 preparation for detachment whatever. 



Thus we have seen that the arrangements under which 

 leaves are shed are exactly repeated in the case of fruits, and 

 that it is by no means needful that the object to be detached 

 should be dead or dying. It may perhaps surprise you to be 

 told that sometimes appendages are shed which have by no 

 means accomplished their prospective work. Some plants 

 shed their flowers and do this deliberately, having made their 

 arrangements for a step which is apparently suicidal. In 

 reality it is not suicidal, nor is it one of limitation of popula- 

 tion, but simply of preferential employment of capital. The 

 potato gives a good example of this. Every spring you may 

 see on the heads of this plant beautiful flowers produced, 

 which are destined in the course of another week to be only 

 flowerless foot-stalks. The flowers break off at a pre-existing 

 joint, just as leaves are shed. The influence which causes 

 them to fall is inability to attract sap, in consequence of 

 inability to proceed to the further stage of producing fruit. 

 The young tubers underground make such overpowering 

 demands upon the sap-furnishing capabilities of the roots that 

 the flowers cannot obtain sufficient for their seed forming. 

 Thus they at once die : if not obviously, at any rate prac- 

 tically, and detachment follows as a natural result. 



