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physiologist who visits the tropics becomes impressed with the 
insufficiency of a science based almost solely upon the study of 
the vegetation of temperate regions, its knowledge of tropical 
plants being for the most part confined to a few isolated ob- 
servations made upon plants grown in European hot houses 
under extremely abnormal conditions. The necessity of survi- 
ving over winter has caused the vegetation of cool temperate 
regions to undergo marked adaptive modifications of very 
special character; whereas in constant warm moist climates 
such as are found in parts of Java, Ceylon, Brazil ete. the 
growth of plants is continuous and influenced by little else 
but the amount of rainfall. Annual plants have arisen by 
special adaption as plants progressed northwards, and all the 
perennial plants of northern Europe exhibit a similar adaptive 
modification, a summer period of intense activity, alternating 
with a period of quiescent hibernation in winter, and it has 
indeed been erroneously supposed that the interposition of 
quiescent or resting periods are essential or at least favourable 
to plant life and development. This is however a fundamental 
error, for under optimal conditions the development of all 
organisms is perfectly continuous from generation to generation, 
and resting periods ensue only in response to unfavourable 
internal or external conditions. 
The warm moist climate of western Java probably corres- 
ponds much more closely to that of the coal period, when 
vegetation attained its maximum development, than our cold 
northern climate does. There can be no doubt that plants 
first appeared on the surface of the globe or rather of the 
ocean when it was much warmer than it is now, and although 
it seems more probable that the thermophile bacteria have 
arisen by secondary adaption, still the possibility remains that 
these organisms may have retained peculiarities which formerly 
characterized all terrestrial vegetation. All meiothermic org@™ 
isms which have no power of maintaining a constant boay 
temperature have been gradually compelled to so adapt them 
selves as to be able to adequately perform their different 
