20 ESSAYS. 
Willdenow from the Berlin garden. It also comprises a por- 
tion of the herbarium of Pallas, the Siberian plants of Stephen, 
and a tolerable set of Humboldt’s plants. This herbarium is 
in good preservation, and is kept in perfect order and extreme 
neatness. As left by Willdenow, the specimens were loose in 
the covers, into which additional specimens had sometimes 
been thrown and the labels often mixed, so that much caution 
is requisite to ascertain which are really authentic for the 
Willdenovian species. To prevent farther sources of error, 
and to secure the collection from injury, it was carefully re- 
vised by Professor Schlechtendal while under his manage- 
ment, and the specimens attached by slips of paper to single 
sheets, and all those that Willdenow had left under one cover, 
as the same species, are enclosed in a double sheet of neat blue 
paper. These covers are numbered continuously throughout 
the herbarium, and the individual sheets or specimens in each 
are also numbered, so that any plant may be referred to by 
quoting the number of the cover and that of the sheet to 
which it is attached. The arrangement of the herbarium is 
unchanged, and it precisely accords with this author’s edition 
of the “Species Plantarum.” Like the general herbarium, it 
is kept in neat portfolios, the back of which consists of three 
pieces of broad tape, which, passing through slits near each 
edge of the covers, are tied in front: by this arrangement 
their thickness may be varied at pleasure, which, though of 
no consequence in a stationary herbarium, is a great conven- 
ience in a growing collection. The portfolios are placed verti- 
cally on shelves protected by glass doors, and the contents of 
each are marked on a slip of paper fastened to the back. 
The herbaria occupy a suite of small rooms distinct from the 
working rooms, which are kept perfectly free from dust. 
Another important herbarium at Berlin is that of Pro- 
fessor Kunth, which is scarcely inferior in extent to the royal 
collection at Schéneberg, but it is not rich or authentic in the 
plants of this country. It comprises the most extensive and 
authentic set of Humboldt’s plants,and a considerable number 
of Michaux’s which were received from the younger Richard. 
As the new “Enumeratio Plantarum” of this industrious 
