Till 
INTRODUCTION. 
so treated: it is formed, by our Maker, as essentially 
distinct from all other species as man is from the brute 
creation ; “ Species tot numeramus, quot diversae forms 
in principio sunt creats Linn. It ought neither for 
convenience to be united with others, nor be split into 
several on account of newly detected diversities of 
form ; but the difficulty is to ascertain what is such a 
primitive or natural species, and how to characterize it, 
so as to include those numerous varieties and individuals 
now existing on the surface of the globe which have 
sprung from it, but of which none may bear greater re- 
semblance to the original or typical form than they now 
do to each other. The history of the human race de- 
monstrates that the descendants of a prototype vary 
much, particularly in external appearance ; but every 
thing stamped by the finger of the Almighty has its 
power of variation limited ; with Him there is no con- 
fusion, no blending of species, although man may not 
with his finite faculties be able to discover the boundaries 
He has assigned to each. It is here so great a difference 
of opinion exists. Some pronounce a species to be 
distinct if it presents a different habit or appearance 
to the eye, particularly if this be tolerably constant, 
although often indefinable : others consider it a species, 
although exhibiting little or no difference of aspect, 
provided that it possesses some constant character, how- 
ever unimportant it may be ; while a third party is of 
opinion that the validity of a species may be proved by 
the permanency of certain assigned characters under 
cultivation. One only of these tests is scarcely sufficient. 
Of the first there are few advocates ; to indicate, indeed, 
ideal species without precise characters in words, by 
which alone others can readily comprehend what is 
meant, whether the specimens be living or dried, would 
be to allow Botany to relapse into a state scarcely better 
then we find it to have been 2000 years ago. The 
