Disapearing organs ......only in the mind of the evolutionist :

There remains, however, this difficulty. After an organ has ceased being used, and has become in consequence much reduced, how can it be still further reduced in size until the merest vestige is left; and how can it be finally quite obliterated? It is scarcely possible that disuse can go on producing any further effect after the organ... has once been rendered functionless. Some additional explanation is here requisite which I cannot give.
Charles Darwin, Origin of Species .
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Lots of evolutionary imagination is the answer ..........................And has been in use since Darwin made this quote .

http://gen1rev22.blogspot.co.uk/2012/05/appendix-still-clearly-in-use.html