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, repre- 

 senting 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 Ger- 

 man 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 embry- 

 ology 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 



[59] 



