Proofs of Evolution. 301 



On the other hand, where opportunities for migration have 

 been favorable, we observe the greatest variety of life. 



Again, if specific centers of creation were the method, each 

 species would be best fitted for its own environment, and 

 could not exist in any other. But the facts show that both 

 animals and plants will flourish far away from their native 

 homes, under totally different physical conditions ; in many 

 cases with decided advantage from the change. 



There are many factors which give rise to diversity of 

 organism as influenced by geographical location, such as 

 temperature, the effect of mountain barriers, and glacial 

 action which induced migration. This subject is so broad 

 and deep that we have only time to mention the remarkable 

 facts concerning the fauna and flora of Australia. Its 

 entire range of animal and plant-life, with trifling excep- 

 tions, is found nowhere else on the globe. Among the 

 great land-areas of the earth, it presents a striking case of 

 retarded evolution, shown alike in species, genera, families 

 and orders. It is a country of synthetic types. We still 

 have there the egg-laying mammals, and the pouched 

 marsupials, of which there are many species ; but of true 

 mammals, there are none. Australia and a few other 

 oceanic islands — notably the Galapagos and Madagascar — 

 seem to be but rudimentary parts of the great body of the 

 globe. Here the tide of Evolution has been checked. Even 

 the natives are among the low r est in the scale of human 

 beings. 



What is the significance of all these facts ? Why should 

 Australia be some ages behind its rivals of like climate and 

 soil ? It is still in the Mesozoic age. The answer is inev- 

 itable. This great island, though doubtless once joined to 

 Asia, lies in complete isolation, thus shutting out the mi- 

 gration of fierce animals ; and those now there have changed 

 but little from earlier types. The reason for this lagging 

 development is the comparative absence of that fierce 

 struggle for existence, which elsewhere prevails. No lion 

 is there to frighten and destroy the kangaroo ; no howling 

 wolves to chase the monotrema. Australia is monkey .less 

 and ape-less, although these animals abound elsewhere in 

 like climates. Wherever the battle for life has been 

 strongest, there we find the greatest progress and variety 

 of development. The dwellers of mid-ocean islands have 

 had an easy, lazy time of it. " Far from the madding 



