438 



8. Vaeiation in the Genus. 



Let me invite attention to what has been written in Part I, p. 1, and Part VIII, 

 p. 246 (" Variation is going on now "). 



The plates of the present work are eloquent as to variation in individual species, 

 even after making allowance for differences of opinion as to whether a few of the forms 

 depicted may possibly be preferably put into adjacent species. 



See also, as almost casual references, " On the General Phenomena of Variation 

 in the Vegetable Kingdom " (Hooker's " Introductory Essay to the Flora of Tasmania," 

 v), and " Darwinism," by A. Russel Wallace, p. 76 (1889), Section on " The Variability 

 of Plants." " The variability of plants is notorious," &c, as, indeed, is the experience 

 of everyone who has come into intimate association with them. 



The first and most common variation resulting from excessive food supply is a 

 general increase in size. This is illustrated by the coastal giants, and the mallees, and 

 also by the dwarf species on exposed mountain tops, dwarfed partly by exposure and 

 partly by deficiency of nutriment. 



" Experience has shown that when once variation of this nature (arising from excessive nutrition) 

 has set in, other variations in shape, texture, colour, flavour, &c, . . . may reasonably be expected." 

 ("Year-book of Agriculture," 1896, p. 92.) 



Turning to another contributing cause — 



" All the phenomena of life have a definite relationship to environment, and therefore, as I shall 

 endeavour to show in this book, the consideration of the configuration of the organs of plants is not merely 

 a comparative historical criticism, but must take into account all the conditions of environment which 

 we find at the present day." (Preface, German edition, " Organography of Plants," Goebel, i.) 



