THE LIVING MACHINE BUILDING FACTORS. 145 



walking appendage, while the bird's wing, by 

 means of some interesting connecting links, can 

 in a similar way be traced to an appendage with 

 its five fingers all free and used for walking. 

 Fig. 49 shows one of these connecting links repre- 

 senting the earliest type of bird, where the fingers 

 and bones of the arm were still distinct, and yet 

 the whole formed a true wing. Thus we see that 

 the common point of origin which is suggested by 

 the likenesses between an arm and a wing is no 

 mere imaginary one, for the fossil record has 

 shown us the path leading to that point of origin. 

 The whole tells us further that nature's method 

 of producing a grasping or flying organ was here, 

 not to build a new organ, but to take one that had 

 hitherto been used for other purposes, and by slow 

 changes modify its form and function until it was 

 adapted to new duties. 



Significance of these Sources of History. The 

 real force of these sources of evidence comes 

 to us only when we compare them with each 

 other. They agree in a most remarkable fash- 

 ion. The history as disclosed by fossils and 

 that told by embryology agree with each other, 

 and these are in close harmony with the history 

 as it can be read from comparative anatomy. If 

 archaeologists were to find in different countries 

 and entirely unconnected with each other two or 

 more different records of a lost nation, the belief 

 in the actual existence of that nation would be 

 irresistible. When researches at Nineveh, for ex- 

 ample, unearth tablets which give the history of 

 ancient nations, and when it proves that among 

 the nations thus mentic-ned are some with the 

 same names and having the same facts of history 

 as those mentioned in the Bible, it is absolutely 



