ORCHIDS AND HYBRIDIZING. 225 
more difficult for this primitive form of orchid to 
exist, and, conscious of the fate impending, it 
gratefully accepts our help. 
One cause of extermination is easily grasped. 
Cypripeds have not the power of fertilizing 
themselves, except a single species, Cyp. Schlimzz, 
which—accordingly, as we may say—is most 
difficult to import and establish; moreover, it 
flowers so freely that the seedlings are always 
weak. In all species the sexual apparatus is 
so constructed that it cannot be impregnated by 
accident, and few insects can perform the office. 
Dr. Hermann Muller studied Cyf. calceolus 
assiduously in this point of view. He observed 
only five species of insect which fertilize it. Cy. 
calceolus has perfume and honey, but none of the 
tropical species offer those attractions, Their 
colour is not showy. The labellum proves to be 
rather a trap thana bait. Large insects which 
creep into it and duly bear away the pollen 
masses, are caught and held fast by that sticky 
substance when they try to escape through the 
lateral passages, which smaller insects are too 
weak to force their way through. 
Natural hybrids occur so rarely, that their exist- 
ence is commonly denied. The assertion is not 
quite exact ; but when we consider the habits of 
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