On the Influence of Climate on Plants and Animals. 119 



the temperate ; their characters are those of different species, 

 not varieties. When we trace the changes in a species of 

 maple, as it approaches the confines of a temperate region? 

 we may estimate the extent of change which is induced by 

 climate. We cannot compare dissimilar species with those 

 which grow in the south ; and, seeing that their differences 

 arise from the influence of climate, because those differences 

 are specific, they should be different ; and they may be 

 greener, straighter, and taller, because those characters be- 

 long to them. But climate has influences, but not the in- 

 fluences in kind by which permanent changes are continued 

 and propagated by the usual modes by which individuals are 

 multiplied, as by cutting, grafting, layers, or budding. Take 

 off the pressure of a cold climate, and the plant which has 

 been pinched and shrivelled, or dwarfed, will mount upwards, 

 and spread itself under a genial sun. It is probable that 

 climate favours the development of certain varieties more 

 than others ; indeed, there can be no doubt of the fact that 

 varieties reach a higher state of perfection in certain climates 

 than in others. If we study the habits of certain fruits, we 

 shall find, and it is a fact well known, that they are very in- 

 ferior, and even valueless, in some climates. The plum is fine 

 and very perfect along the Hudson River ; but a few miles 

 distant from it, it becomes inferior in quality. While, how- 

 ever, it is sufficiently manifest that varieties do not originate 

 under the forces incident to climate, it is still difficult to point 

 to causes which are directly operative in their production : it 

 is, however, probable that a parental influence, those in- 

 fluences perhaps which are implanted for wise purposes, are 

 effective in their development. Those species which are re- 

 presented under numerous varieties, as the fruits and domes- 

 ticated animals, have implanted in them a susceptibility to 

 undergo those changes in their constitutions — it is, in fact, 

 a part of their specific character ; it is of a higher grade in 

 some of the domesticated animals than others, and it is inci- 

 dent to those animals only which can be domesticated ; and 

 those which are easily domesticated have the power of mul- 

 tiplying varieties in the greatest numbers, and display the 

 widest differences in the extremes. These views apply to 



