[78] "Descent of Man," p. 155.
[79] "Biology," i, p. 366.
[80] "In the presence of the various genealogical trees of animal descent which have been put forward so frequently of late, a judicious skepticism seems the attitude best warranted by the evidence yet obtained. If so many similar forms have arisen in mutual independence, then the affinities of the animal kingdom can never be represented by the symbol of a tree. Rather, we should conceive of the existence of a grove of trees, closely approximated, greatly differing in age and size, with their branches interlaced in a most complex entanglement. The great group of apes is composed of two such branches; but their relations one to another, to the other branches which represent mammalian groups, and to the trunks from which such branches diverge, are problems still awaiting solution."—"Encyclopædia Britannica," article "Apes."
[81] "Biology," i, pp. 380-382.
[82] I use these terms with quotation-marks, because I do not admit any philosophical antagonism such as they are intended to imply.
[83] "Homology" is defined by lexicographers as "the doctrine of similar parts." "Homologous organs" is a term used by scientific writers to describe organs having a relation of some proportion to each other. In this particular case of the vertebral column, the different parts of the column are treated as if they were different organs, and they are said to be homologous organs in the same animal, because they bear a certain relation or ratio of proportion to each other.
[84] See the discussion of how evolution works, post.
[85] "Biology," i, p. 387.
[86] The Greek philosophers, as we have seen, before Plato and Aristotle, found that their systems of causes, which did not involve the idea of power as abstracted from substance, would not account for the phenomena of nature. With all their subtilty and ingenuity, they did not reach the truth that secondary causes are necessarily limited in their action, and that there must be an unlimited cause.
[87] "Biology," i, pp. 369, 370.