Kll 
PREFACE. 
that in all cases where I do draw upon it I shall be careful 
to state the source to which I am indebted. 
[The above was written when I sent this work to the 
publishers several months ago, and I have thought it 
best to leave the concluding paragraph as it originally 
stood. But in making this explanation, I cannot allude 
to the calamity which has since occurred without paying 
my tribute, not alone to the memory of the greatest 
genius of our age, but still more, and much more, to the 
memory of a friend so inexpressibly noble, kind, and 
generous, that even my immense admiration of the 
naturalist was surpassed by my loving veneration for the 
mam] 
