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tions apparently of no direct service-Progressive development

—Characters of small functional importance, the most con-

stant—Supposed incompetence of natural selection to account

for the incipient stages of useful structures—Causes which in-

terfere with the acquisition through natural selection of useful

structures—Gradations of structure with changed functions—

Widely different organs in members of the same class, de-

veloped from one and the same source-Reasons for disbeliev-

ing in great and abrupt modifications - - - . 262

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