416 NATURAL SYSTEMS OF CLASSIFICATION. 
artificial, so that all that we mean by a Natural System is, that 
it expresses, as far as is possible only, the arrangement of plants 
according to their natural affinities. (See page411.) This imper- 
fection of our natural systems necessarily arises from our incom- 
plete knowledge of existing plants ; for as our acquaintance with 
new species is becoming every day extended, our views are liable 
to be modified or changed, and even supposing plants be ever 
so naturally arranged, we should be still unable to place them 
in a linear series, for ‘ Different groups touch each other at 
several different points, and must be considered as alliances con- 
nected with certain great centres. We find also that it is by no 
means easy to fix the limits of groups. There are constantly 
aberrant orders, genera, and species, which form links between 
the groups, and occupy a sort of intermediate territory. In 
this, as in all departments of natural science, there are no sud- 
den and abrupt changes, but a gradual transition from one 
series to another. Hence exact and rigid definitions cannot be 
carried out. In every natural system there must be a certain 
latitude given to the characters of the groups, and allowances 
must be made for constant anomalies, in so far as man’s defini- 
tions are concerned.’ 
NatTurAL Systems.—We now proceed to give an abstract of 
the more important natural systems. The first attempt at 
arranging plants according to their natural affinities was by 
our celebrated countryman, John Ray, in the year 1682; and 
imperfect as any scheme must necessarily have been at that day, 
when the number of plants known was very limited, still his 
arrangement was in its leading divisions correct, and has formed 
the foundation of all succeeding systems. He divided plants 
thus :— 
1. Flowerless. 
2. Flowering ; these being again subdivided into 
a. Dicotyledons. 
b. Monocotyledons. 
Ray still further grouped plants together into genera, which were 
equivalent to our natural orders, many of which indicated a true 
knowledge of natural affinities, and are substantially represented 
at the present day by such natural orders as the Fungi, Musci, 
Filices, Coniferze, Labiatze, Composite, Umbelliferze, and Legu- 
minosz. 
Next in order was the scheme propounded by the celebrated 
author of the most perfect artificial system ever devised for the 
arrangement of plants, namely, Linnzeus, who, about the year 
1751, drew up a sketch of the natural affinities of plants under 
the name of Fragments. Many of the divisions thus prepared by 
_ Linnzeus are identical with natural orders as at present defined, 
among which we may mention Orchidez, Gramina, Composite 
(nearly), Umbellatee, Asperifoliz, Papilionacez, Filices, Musci, 
and Fungi. 
