PREFACE Vv 
most varied kind,—that wide and accurate physio- 
logical knowledge,—that acuteness in devising and 
skill in carrying out experiments,—and that admirable 
style of composition, at once clear, persuasive and 
judicial,—qualities, which in their harmonious combi- 
nation mark out Mr. Darwin as the man, perhaps of 
all men now living, best fitted for the great work he 
"has undertaken and accomplished. 
My own more limited powers have, it is true, enabled 
me now and then to seize on some conspicuous group 
of unappropriated facts, and to search out some gene- 
ralization which might bring them under the reign 
of known law; but they are not suited to that more 
scientific and more laborious process of elaborate in- 
duction, which in Mr. Darwin’s hands has led to such 
brilliant results. , 
Another reason which has led me to publish this 
volume at the present time is, that there are some im- 
portant points on which I differ from Mr. Darwin, and 
I wish to put my opinions on record in an easily 
accessible form, before the publication of his new 
work, (already announced,) in which I believe most 
of these disputed questions will be fully discussed. 
I will now give the date and mode of publication of 
each of the essays in this volume, as well as the amount 
of alteration they have undergone. 
J.—On tHe Law watch Has REGULATED THE InTRO- 
pDucTION oF New SPECIES. 
First published in the “Annals and Magazine of 
