DEVELOPMENT OF THE ORGANISM
by fossils. When we study the fossils preserved in a great mass of strata, overlying one another like the pages in a gigantic book, we find some of these fossil animals gradually changing as we pass up the series. In the Devonian strata we find numerous remains of fish with fins consisting of a central axis beset with two rows of branches like a feather. As we reach the base of the Carboniferous strata these give place to newts with five-fingered hands and feet. An eminent palaeontologist (Prof. D. M. S. Watson, F.R.S.) who has studied this series of fossils, arrived at the conclusion that the fourth finger on the hand represented the axis of the feather, that the fifth finger was the sole remaining branch on one side, and that the first three fingers were the branches on the other side. A German embryologist, who was totally ignorant of Dr. Watson's conclusion, studied the early development of the wing of the common fowl. Here, in the youngest stage, five columns of condensed tissue, representing the five fingers, can be made out, though in the adult bird only two and the trace of the thumb remain. From a study of the growth of these rudimentary fingers the German arrived at the same conclusion that was reached by Dr. Watson from his study of the fossils, namely, that the fourth finger represents the axis of the fin. Thus, when the opportunity is afforded, the conclusions drawn from embryology are confirmed by palaeontological evidence. Other examples of the same confirmation could be given, but their citation would involve detailed descriptions of anatomy. As, however, these confirmations are increased in number, our confidence in the truth of the embryological record grows; and this confidence is of the utmost importance to us for tracing the history of evolution, because this ancestral record, repeated in embryonic development, gives us the only means that we possess of tracing the history of life back to
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