. 
J. D. Hooker, Introductory Essay to the Flora of Tasmania. 5 
relationship; and the facts that individuals are more easily — 
grouped into species limited by characters, than into varieties, 
or than species are into limitable genera or groups of higher 
value, and that the relationships of species are transmitted he- 
reditarily in a very eminent degree, are the strongest appear- 
ances in favor of species being original creations, and genera, 
etc., arbitrarily limited groups of these. 
The difference between varieties and.species and genera in re- 
spect to definable limitation is however one of degree only, and 
if increased materials and observation confirm the doctrine which 
I have for many years labored to establish, that far more species 
are variable, and far fewer limitable, than has been supposed, 
that hypothesis will be proportionally strengthened which as- 
sumes species to be arbitrarily limited groups of varieties. With 
the view of ascertaining how far my own experience in classifi- 
cation will bear out such a conclusion, I shall now endeavor to 
review, without reference to my pe conclusions, the im- 
$2. On the General Phenomena of Variation in the Vegetable — 
Kingdom. 
1. All vegetable forms are more or less prone to vary as to 
their sensible properties, or (as it has been peppy ex ressed in 
regard to all organisms), “ they are in a state of unsta le equili- 
brium.”* No organ is exactly symmetrical, no two are exact 
* Essays: Scientific, Political, and Speculative; by Herbert Spencer: p. 280. 
—— 
ae 
