Plant Families : A Plea for International Sequence. 267 
volume. The precise assignment of these numbers is a matter 
of secondary importance in comparison with the advantages which 
come from their use. 
Standard family numbers if established as a result of general 
consideration, thus dividing the world of plants along definite 
lines easily designated, might have various uses, for example :— 
(a) They would be likely to give direction to morphological 
investigations. 
(b) If lists of plants growing in many different parts of the 
world had the degree of unity implied by uniform family numbers, 
they would to a much greater degree than at present form a part 
of one work: the flora of the earth. Such lists would tend towards 
greater uniformity of nomenclature. 
(c) Perhaps the time is yet distant when descriptive floras 
throughout the world may be arranged by a single system. Should 
it come the solution of numerous questions as to characters and 
distribution could not but be facilitated. 
(d) Seed lists of botanic gardens, issued annually, are now 
arranged by a dozen different methods. Uniformity even among 
a few gardens would simplify exchanges and would naturally lead 
to increased co-operation. 
( e ) Botanical gardens cannot cultivate all plants, but wish to 
know: what are the plants of the world of greatest horticultural, 
economic or scientific interest? Uniformly arranged planting 
lists would tend in the direction of an answer, simplifying the 
work and increasing the value of collections. 
(/) In the arrangement of numerous herbaria and other 
collections, especially smaller ones, such as those connected with 
instruction, where it is desirable that the arrangement should not be 
too distant from current views. 
If after a period of years, preferably longer than ten, a different 
set of numbers should be adopted, this would only very slightly 
interfere with their benefits. Possibly alternate lists might make 
needed changes by inserted letters a, b, c as has been done by Engler. 
In any case hardly more than a pamphlet would be required to refer 
from the ten or twelve thousand genera of vascular plants 
as ordinarily used directly to family numbers, accompanied 
by abbreviated family names. The inclusion of genera in 
an index wouLd not need to imply any recognition of the 
names. However, at some future time uniform families might 
naturally lead to an extension of the principle of genera conservanda. 
