Cyp. purpuratum is almost extinct at Hong Kong, and is vanishing fast on the mainland.  It is still found occasionally in the garden of a peasant, who, we are told, resolutely declines to sell his treasure.  This may seem incredible to those who know the Chinaman, but Mr. Roebelin vouches for the fact; it is one more eccentricity to the credit of that people, who had quite enough already.  Collectors expect to find a new habitat of Cyp. purpuratum in Formosa when they are allowed to explore that realm.  Even our native Cyp. calceolus has almost disappeared; we get it now from Central Europe, but in several districts where it abounded the supply grows continually less.  The same report comes from North America and Japan.  Fortunate it is, but not surprising to the thoughtful observer, that this genus grows and multiplies with singular facility when its simple wants are supplied.  There is no danger that a species which has been rescued from extinction will perish under human care.

This seems contradictory.  How should a plant thrive better under artificial conditions than in the spot where Nature placed it?  The reason lies in that archaic character of the Cypriped which Darwin pointed out.  Its time has passed—­Nature is improving it off the face of the earth.  A gradual change of circumstances makes it more and 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.  Schlimii, 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 Cyp. calceolus assiduously in this point of view.  He observed only five species of insect which fertilize it. Cyp. 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 than a 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 existence is commonly denied.  The assertion is not quite exact; but when we consider the habits of the genus, it ceases to be extraordinary that Cypripeds rarely cross in their wild state.  Different species of Cattleya, Odontoglots, and the rest live together on the same tree, side by side.  But those others dwell apart in the great majority of cases, each species by itself, at a vast distance perhaps from its kindred.  The reason for this state of things has been mentioned—­natural laws have exterminated them in the spaces between, which are not so well fitted to maintain a doomed race.