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of allied whole groups of allied organic beings, & not on from considering any single animal, whether it be a dog, horse, or man. For it is only very considering whole groups of beings that the weighty arguments deduced from this classification & or natural affinities,— their geographical distribution in past & present time,— & their geographical succession can be brought to bear. When we discuss the case of any [text obscured] which these remain little

[Descent 1: 2: "When we confine our attention to any one form, we are deprived of the weighty arguments derived from the nature of the affinities which connect together whole groups of organisms—their geographical distribution in past and present times, and their geological succession. The homological structure, embryological development, and rudimentary organs of a species, whether it be man or any other animal, to which our attention may be directed, remain to be considered; but these great classes of facts afford, as it appears to me, ample and conclusive evidence in favour of the principle of gradual evolution. The strong support derived from the other arguments should, however, always be kept before the mind."]