22 Rhodora [FEBRUARY 
is or should be well known, however, that the specimens in the Lin- 
naean Herbarium are not types in the modern sense (except in rare 
cases, when Linnaeus’s species were based entirely on specimens in 
his herbarium at the time of publication), and their identity is often 
only of minor significance. It was Linnaeus’s practice to add at any 
time specimens which he considered to represent species described in 
the Species Plantarum or other works, which has in the past been a 
source of some confusion to botanists who have examined his her- 
barium. Through the careful studies of Mr. B. Daydon Jackson,! 
now fortunately accessible to all, it is possible to learn the date of 
accession of all specimens in the Linnaean Herbarium, and thus to 
estimate their value as representatives of the Linnaean species. 
Too much stress has been laid, especially by modern geneticists, 
on an assumed fundamental difference between Linnaean and modern 
ideas of species. The Linnaean species, properly considered, was not a 
mere aggregation of more or less closely related entities, but in its 
essentials identical with the specific units of the great majority of 
reputable botanists since his time. Composite and sometimes hope- 
lessly confused species he had, but they were due in great part to the 
fact that his material was so largely merely bibliographical, and even 
modern botanists have sometimes based new specific names on speci- 
mens in hand which when examined by other workers have been found 
to represent not merely two or more species but sometimes even dis- 
tinct genera. The gradual tightening of specific lines, from Lin- 
naeus’s day to our own, has been due in the main not to an alteration 
of ideas but to more careful study of better and more abundant mate- 
rial, and to the discovery of constant and significant differences in the 
smaller and less obvious structures of the plant formerly little attended 
to. The conflict in the specific ideal comes not between that of 
Linnaeus and that of the modern systematist, but between the latter 
and that of the geneticist, and its settlement must be left to the future. 
If then the Linnaean species, when an aggregate, differs in no 
essential from any modern aggregate species, how is it to be typified? 
Only in exceptional cases can the Linnaean Herbarium solve the ques- 
tion. The “first citation” method, although it may sometimes be of 
service, is surely not to be adopted as an arbitrary rule. The principle 
of the “name-bringing synonym,” likewise, though often useful, is by 
1B. D. Jackson, “Index to the Linnean Herbarium,” Proc. Linn. Soc. 124th Sess. Suppl. 
1-152 (1912). 
