726 On the Natural Succession of the Dicotyledons. | November, 
more permanent or reliable, or that they are more compre- 
hensive, and better typify the general sum of the characters 
distinguishing groups of plants, a point in their favor would be 
gained, but, as we shall see, such is not the case. In point of 
fact these characters frequently change when nothing else has 
changed, and often remain the same when everything else widely 
differs. They constantly tend to “run together,’ and no strict, 
dividing line exists between them. They also frequently vary 
within very narrow groups, sometimes in the same species or 
individual. Critically viewed, therefore, this system so far as it 
goes, presents as many imperfections and stands as directly in the 
way of the adoption of a truly natural system as did the profess- 
edly artificial one of Linnzus. 
The recognition of the three Divisions, as is made in nearly 
all systematic works on botany, even the most recent, involves 
numerous direct conflicts with the best established orders of 
dicotyledonous plants. Many orders are found to contain species 
and genera whose corollas would require them to be placed in a 
different Division from that in which the order itself has been 
placed. Examples of this class are abundant. Paronychia, a 
genus which seems clearly to belong to the polypetalous order 
Caryophyllacee (Illecebree), is usually apetalous, though some 
species retain a rudiment’ of the petals in the form of minute 
teeth or bristles; Chrysosplenium in the order Saxafragace@ is 
another example of the same class. G/aux in the monopetalous order 
Primulacee is destitute of a corolla. Ludwigia, Ammannia, Pen- 
thorum, Nyssa, are further illustrations, and only the most familiar 
need be mentioned. Most of the Auphorbiacee in this country (if 
we except £uphorbia itself), which are monoecious, have polypet- 
alous staminate (male), and apetalous fertile (female) flowers. 
_ Here we have the two extreme divisions united in the same indi- 
_ vidual plant (Croton, Tragia, etc.). 
1 The term “ vestige” ? would probably be more correct. It is certainly remarkable 
that this term has not been more generally adopted to express this important disting: 
: tion so clearly. perceived by the naturalists of this e epoch. The terms “rudime nt” 
and “rudimentary ” should be confined to those organs which the life- ppe of the 
plant or animal shows to be in process of development or formation. On the other 
; hand those organs which, from disuse or other causes, have dwindled into mere rem- 
; of once perfect ones should be distinguished by the term “ vestiges” oran 
equally appropriate and expressive one. Yet these are the so-called “ rudimentary 
organs? which have played so pa a rôlein the modern theories of science, and 
Darwin himself e i n i in that sense without commenting 0P- 
