M HISTORICAL SKETCH 



that such an assumption is as unsupported by tradition 

 or revelation as it is opposed to the general analogy of 

 nature. If, on the other hand, we view 'Persistent 

 Types' in relation to that hypothesis which supposes 

 the species living at any time to be the result of the 

 gradual modification of pre-existing species — a hypothesis 

 ■which, though unproven, and sadly damaged by some of 

 its supporters, is yet the only one to which physiology 

 lends any countenance — their existence would seem to 

 show that the amount of modification which liring be- 

 ings have undergone during geological time is but very 

 small in relation to the whole series of changes which 

 they have suffered." 



In December, 1859, Dr. Hooker published his "Intro- 

 duction to the Australian Flora." In the first part of 

 this great work he admits the truth of the descent and 

 modification of species, and supports this doctrine by 

 many original observations. 



The first edition of this work was published on No- 

 vember 24, 1869, and the second edition on January 7, 

 1860. 



