GENERAL DESCRIPTION 
11 
each other by any one character, bnt by the combination 
of their characters. For this reason a plant may have 
one of the characters of a class to which it neverthe- 
less does not belong, because its other characters are 
at variance with that class. Thus some species of 
Ranunculus have the flowers with their parts in 
threes ; but they do not on that account belong to 
Endogens, because their wood is concentric, their 
leaves netted, and their embryo dicotyledonous. 
Arum maculatum has reticulated leaves ; but it is not 
an Exogen, because its wood is confused, and its 
embryo monocotyledonous ; its flowers are neither in 
fours or fives nor threes, all the parts being in a state 
of peculiarly diminished structure. The genus Pota- 
mogeton (a water plant, one of the Naiads) has the 
flowers in fours ; yet it does not belong to Exogens, 
because its leaves have parallel veins, and its embryo 
is monocotyledonous.” 
No better words could have been written, whether 
to stimulate the learner to care and thoroughness in 
research or to rebuke the dogmatism of pedantic 
system- builders and teach that modesty and liberal 
allowance of dissent which should characterize the 
student of Nature and the worshiper of Truth. 
