198 SPECIES NOT 



similarity of parts in the former than in the 

 latter. But I must leave this question to be 

 settled by botanists: I merely now enter my 

 protest against the analogy of the fed-up abnor- 

 mities from the vegetable world being adduced 

 in support of the assumed change of organic 

 structure, which would be necessary to convert 

 a bear into a whale, or a nightingale into a 

 pelican. 



In the paper above alluded to, by Dr. Asa 

 Gray, there are some further illustrative remarks, 

 which I will quote. 



"Similarity of climate does not necessarily 

 indicate similarity in the floras of two countries. 

 The vegetation of Australia is a signal illustration 

 of the fact, being of a very peculiar type. The 

 distribution of plants on the earth's surface is 

 limited by natural laws, such as the interposition 

 of large bodies of water, of high and snowy 

 ranges of mountains, or of rainless regions, such 

 as . those of the Pacific coast. But the most 

 stringent of these laws is the law of climate, as 

 marked out by the isothermal lines. It is 

 because the presence of the same species in this 

 country and in the Upper Himalaya region appears 

 to transgress this law of climate, that the fact 

 seems so strange. 



"But we must remember that since the period 

 of the formation of the tertiary rocks the climate 

 of this portion of the earth has gone to two 

 great and opposite extremes. During the fluvial 

 period the temperature of the Arctic regions 



