Transmutation Notebook B, Tree of Life
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Case must be that one generation then should be as many living as now To do this & to have many species in same genus (as is). REQUIRES extinction.
Thus between A. & B. immens gap of relation. C & B. the finest gradation, B & D rather greater distinction
Thus genera would be formed.— bearing relation
to ancient types.— with several extinct forms, for if each species an ancient (I) is capable of making, 13 recent forms.— Twelve of the contemporarys must have left no offspring at all, so as to keep number of species constant.— With respect to extinction we can easily see that variety of ostrich, Petise may not be well adapted, & thus perish out, or on other hand like Orpheus. being favourable many might be produced.— This requires that the permanent varieties produced inter confined breeding & changing circumstances are continued & produce according to the adaptation of such circumstances & therefore that death of species is a consequence (contrary to what would appear from America) of non adaptation of circumstances.—