656 TRANSACTIONS OF SECTION K. 
with a family B and only two with a family C, while the characters combined 
in A are, as regards B and C, mutually exclusive, the organographic syste- 
matist is ordinarily induced to group A and B together and to exclude © 
from that particular aggregation of families. If, on the other hand, the 
phylogenist finds that the two characters common to the families A and C are 
met with in other families, D, H, F, he will ordinarily be led to place A, C, 
D, E, F in the same higher group from which the family B, notwithstanding 
its greater general agreement with A than any of the others, must be excluded. 
This source of discrepancy is, however, less potent than might be expected. 
When the evidence advanced by eithersis very strong, the other worker readily 
accepts it; in doubtful cases mutual accommodation takes place, the one 
worker limiting his groups, the other applying his criteria with less rigidity. 
The healthy disregard for formal consistency which admits of adjustments 
to further practical ends does not, however, alter the fact that a system thus 
attained can only approximate to the natural arrangement at which both 
workers aim. Gaps in knowledge may be bridged with histological or terato- 
logical aid, or safely crossed with the help of some sudden intuition or happy 
speculation. But the existence of anomalous types and groups serves as a 
reminder that much has yet to be learned with regard to living types, while 
the widest gap in our knowledge of these is a fissure as compared with the 
chasms that confront the paleontologist. In this the taxonomist of either 
type finds the incentive to further effort. 
The automatic adjustment of differences due to idiosyncrasy, and the 
mutual accommodation of those arising from method of work, still leave 
considerable want of harmony in taxonomic results to be accounted for. 
What appear to be rival systems of classification compete for recognition. 
As each such system professes to be the nearest attainable approximation to 
the natural arrangement, the evidence of a state of dissension and confusion 
in the taxonomic field appears to those unfamiliar with systematic work to be 
incontrovertible. Dissension may be admitted; confusion there is none. 
Pictures of the same subject by different artists may be very unlike, yet 
equally true ; what appear to be rival systems are only manifestations of one. 
It is not difficult to form a conception of this system; it is less easy to 
share the conception with others. Let us imagine a closed space approxi- 
mately spherical in shape, its surface studded with symbols that mark the 
relative positions of existing plant-types. Let us imagine the lines of descent 
of all these types to have been definitely traced and effectively mapped. We 
find, starting from near the centre of our sphere, a radiating system of lines; 
we find these lines to be subject to repeated dichotomy and embranchment 
which may take place at any point ; we find the resultant lines departing from 
the original direction at any angle and in any plane; we find the nodus of any 
individual dichotomy or embranchment capable of serving as the focus of 
origin for a subsidiary system comparable in everything except age with the 
centre of our sphere, and conceivably exceeding in the multiplicity of its rami- 
fications the primary system itself. Some only of our lines reach the symbols 
that stud our spherical surface, though every symbol is the terminal of some 
such line. Here a terminal is fairly isolated, and the line it limits goes far 
towards the centre with little or no dichotomy or embranchment. Elsewhere 
our terminals are closely set, the lines they limit running inwards in company 
till some proximate nodus is reached. Moreover, within our sphere, in the 
abrupt terminals of various lines we can dimly trace the vestiges of other 
spheres, not always concentric with our present sphere, once studded with 
symbols marking the existence of types now extinct. Imagine further the 
centre of our hypothetical space as not necessarily a primary centre, but 
merely the nodus of some dichotomy or embranchment in a system of which 
ours is but a residuary fragment. 
As we are practically limited to superficial delineation, an intelligible 
picture of our system is more than the science of perspective and the art of 
