36 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
AS DYESTUFFS. 
Dyes of various colors have been extracted from lichens. The 
colors are usually reds, purples, or blues, and the dyes have been 
used for coloring cloth, wood, paper, ete. In Kurope they have been 
quite largely employed in coloring homespun cloth and yarn, our 
common Parmelia sazatilis being ordinarily used, producing various 
colors according to the method employed in making the dye. In 
Kvernia vulpina the yellow coloring matter is ready formed in the 
thallus, and the same may be said of the beautiful yellows and 
oranges of our Teloschistes and Placodiums. Brown colors are also 
ready formed in many lichen thalli, are easily extracted, and have 
been used for home consumption. 
Most of these dyes are not to be had in suflicient quantities to be 
manufactured for the markets. However, Roccella tinctoria, a lichen 
found on our Pacifie coast and on various coasts of the Old World, 
produces a pigment which has been known by one name or another 
since earliest historical times. ‘Orseille’’ is one of its names and 
“litmus” another. This is no doubt the ‘blue and purple” of the 
Old Testament, and in more recent times the same dye has been 
extensively used in France for coloring silks. At the present time 
paper is colored with a neutral solution of the dye-and used commonly 
in chemical laboratories as litmus paper. Litmus is also found in 
the market as a carmine powder and as an indigo blue. In obtaining 
these lichen dyes, the thallus is pulverized and then some alkali is 
applied for the extraction of the coloring matter. 
AS RELATED TO THE WELFARE OF TREES. 
In France and other countries of Europe foresters have supposed 
that lichens are injurious to the trees and have to a limited extent 
practiced scraping the larger ones from the bark, along with certain 
other fungi. However, it would be difficult to accomplish much in 
this way in large forests, even were it known that the lichens are very 
injurious to the trees. In our country M. B. Waite, while experi- 
menting with fungicides on fruit trees, noted that. the Bordeaux 
mixture killed the lichens very effectually. He is not at all certain 
that the lichens are injurious to the trees, but thinks that they may 
at least interfere with the functions of the bark. Tt is true that the 
more conspicuous foliose lichens are more common on unhealthy 
trees than on thrifty ones (pl. 37, facing p. 195), but the question 
remains whether the lichens have worked the injury to the trees or 
whether unhealthy trees are more easily penetrated by the rhizoids 
of the lichens, and also whether they furnish some food materials for 
the lichens not present in healthy trees or not easily obtained from 
them. It is probably not worth while to take time to remove lichens 
from any trees of temperate regions for the sake of saving the trees 
from injury. 
