PREFACE. 
Tue series of papers collected in this volume 
may be considered as a complement or commen- 
tary to my “Essay on Classification,” since I 
have endeavored to present here in ‘a more pop- 
ular form the views first expressed in that work. 
And although the direct intention of these pages 
has been, as their title indicates, to give some 
general hints to young students as to the meth- 
ods by which scientific truth has been reached, 
including a general sketch of the history of sci- 
ence in past times, yet I have also wished to 
avail myself of this opportunity to enter my ear- 
nest protest against the transmutation theory, 
revived of late with so much ability, and so 
generally received. It is my belief that natural- 
ists are chasing a phantom, in their search after 
some material gradation among created beings, 
by which the whole Animal Kingdom may have 
been derived by successive development from a 
