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the external conditions, and may finally become so perma- 
nently fixed that its fulfillment is essential for continued 
existence. Induced or periodic variations of obscure origin may 
often deprive physiological experiments of their necessary 
exactitude, and hence it is of the utmost importance that the 
plants should not merely be kept under constant conditions 
during experimentation, but that they should from the first be 
grown under conditions which undergo as little alteration as 
possible, so that the confusing effects of induced periodic va- 
riations may be avoided. Changes in the external world are 
of importance from a phylogenetic point of view owing to the 
fact that they may give rise to automatic internal variations, 
by the selection of which adaptive modifications may be pro- 
duced, but there can be no doubt that any plant with definite 
specific peculiarities could be grown and could reproduce its 
kind for ages under optimal and perfectly constant external 
conditions, so long as it was protected from outside competi- 
tion. The vegetation of western Java is subject only to the 
periodicity induced by the inevitable alternation of night and 
day, and to the succession of the wet and less wet monsoons. 
Hence fewer disturbing factors enter into play, and the different 
functions pursue comparatively straight paths, so that the 
vegetation in a climate like that of W. Java is eminently 
adapted for the study of the intimate physiological relationships 
which underlie all manifestations of vital activity. 
The above short sketch may serve to give some idea of the 
wealth of physiological research which the tropics present to 
the trained physiologist, and for an y ordinary research the 
Buitenzorg botanical laboratories offer ample facilities, since 
as regards the thoroughness of their equipment they compare 
favourably with most European botanical establishments and 
are surpassed by but few. 
Juli 6th 1898. Botanical Department. 
Magdalen College. Oxford. 
‘rattan gen erie 
