Heredity conserves the old or existing types. Evolution pro- 
duces something new, different from the old, but how or why, no 
one can really say with certainty. What determines whether a 
new form so produced shall continue to exist? Under conditions 
of civilization, survival value depends on utility, practical or 
PLATE II 
LEAVES OF BOSTON FERN VARIETIES ILLUSTRATING A DIVISION SERIES 
I Vat. ' bostoniensis.’ 2. ‘ Piersom ’ 3. ' Whitmani.' 
4. ‘ Magnifica. 3. ‘Craigi ’ 
decorative, to man. Man selects from among wild ferns those 
forms most desirable in his eyes, and most easy to grow. From 
among their variations, he has selected those new forms which 
further possess the same qualities. Nature, on the other hand, 
demands not necessarily beauty in form, but, among other 
qualities, particularly vigor of growth, and ability to survive 
adverse conditions. It will be a matter of exceptional scientific 
* From Hull. Torrey Club. 43: pi. 10. 191H. 
D 
