34 
in diameter. The pressure is applied by a small screw at each 
end. Between the plates are two sheets of ox-hair felt, each one 
inch thick. 
The specimens to be dried are laid directly on the felt, with- 
out paper, and the press screwed up as tight as can be done with 
the thumb and finger, to flatten the specimen ; then laid flat down, 
preferably where there is a draft or breeze, propping up the wind- 
ward end 4 or 5 inches to allow the air to pass under it. At the 
end of six or twelve hours the press is opened to ascertain if the 
plants have become limp. If so, the press is left open twenty or 
thirty minutes. The felt and upper plate are then replaced, but 
not screwed down. In this condition it is left until dry, which is 
from one to four days. If the plants show any trace of shrivel- 
ling, the screws are applied again to flatten them out. 
When dry, the plants are laid between loose sheets of paper 
for at least four weeks, when they are poisoned. If poisoned 
sooner, the color in some species is much injured. Ballast plants, 
however, are poisoned as soon as they are out of the press, as the 
small insect, Atropos pulsatoria, is sometimes found on them in the 
- field. In poisoning all specimens, be careful to poison the end of 
‘the stem. Advopos attacks the most tender parts first, and gets 
into the pith of the stem. By poisoning that, he is stopped at 
once. 
There are a few species in which one sheet of paper under 
and over the plant is used to keep it from the felt; Galium 
asprellum, on account of the hooked prickles; Cuphea viscosis- 
sima is sticky all over; Tipularia discolor has large, waxy pollen 
masses, which, in drying, form a cement as hard and strong as 
glue, and the flowers of Azalea viscosa, are sticky. The thistles have 
Straight spines, and do not require paper. The use of heat, either 
fire or sunshine, is a disadvantage, turning the plant black. 
Standing the press on end or on edge is a disadvantage, delaying 
the drying. The greater part of the moisture leaves the plant in 
a vertical line. When the press is on edge the moisture rises 
across the whole page by the longest and slowest line. When 
laid flat down it rises through the leaves and through the felt by 
the shortest and quickest line. CHARLES E. SMITH, 
: ; 216 South Fifteenth Street, Philadelphia. 
