mSTORIOAL SKETCM. xt 



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 modifica- 

 tion which living beings 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 modifica- 

 tion of species, and supports this doctrine by many original 

 observations. 



The first edition of this work was published on Novem- 

 ber 24, 1859, and the second edition on January 7, 1860. 



