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234 lived. Thus the subject of Homology gains largely in interest.

Although this subject, under whatever aspect it be viewed, will always be most interesting to the student of nature, it is very doubtful whether the following details on the homological nature of the flowers of Orchids will possess any interest for the general reader. If, indeed, he cares to see how much light an acquaintance with homology, though far from perfect, throws on a subject, this will, perhaps, be nearly as good an instance as could be given. He will see how curiously a flower may be moulded out of many separate organs,—how perfect the cohesion of primordially distinct parts may become,—how organs may be used for purposes widely different from their proper uses,—how other organs may be entirely suppressed, or leave mere useless emblems of their former existence. Finally, he will see how enormous has been the amount of change which these flowers have undergone from their parental or typical form.

Robert Brown first clearly discussed the homologies of Orchids, and left, as might be expected, little to be done. Guided by the general structure of monocotyledonous plants and by various considerations, he propounded the doctrine that the flower properly consists of three sepals, three petals, six anthers in two whorls or circles (of which only one anther belonging to the outer whorl is perfect in all the common forms), and of three pistils, with one of them modified into the rostellum. These fifteen organs are arranged as usual, alternately, three within three, in five whorls. Of the existence of three of the anthers in two of