82 
ANNALS OF THE 
between Sticta pulmonaria and Cetraria Islandica, the "well-known " Iceland Moss." 
Like that Lichen, Sticta pulmonaria contains gum, starch, bitter and astringent 
principles, and a brownish colouring matter. Its nutritive and demulcent proper- 
ties depend upon the presence of the former two, viz., the gum and starch. The 
starch, however, contained in it is of too small an amount to be of itself of much 
practical use. An article of diet which is said to be very light and pleasant is, 
with little difficulty, obtainable from this plant in the following way : — After hav- 
ing thoroughly disengaged from it all extraneous substances, let it be steeped in a 
weak solution of some alkali, as of carbonate of soda, or potash, in order to neutral- 
ize the effect of the bitter principle, already mentioned as existing in it, which 
would otherwise impart a disagreeable taste to the article to be prepared. Then 
let it be taken out and floated in cold water for a minute or two, that any of the 
solution adhering to it may be removed. On being boiled for a short time in 
water, sugar having been added during the process, and then allowed to cool, it 
will be found to yield a jelly of a brownish hue, which is due to the presence of 
colouring matter, extracted by the boiling water. To give the jelly an additional 
flavour, wine or spices may be added. It was, at one time, in Britain, a favourite 
article of diet for invalids. Secondly, in regard to its employment as a medicine. 
In media3val medicine, in Britain, as well as other countries, Lichens were very 
extensively employed, chiefly as demulcents, purgatives, tonics, astringents, febri- 
fuges and nutrients. Several were lauded as sovereign remedies in particular dis- 
eases. For ir^stace, the common Peltigera canina was the basis of the celebrated 
pulvis contra rabiem," or " pulvis antilyssus," the alleged never-failing cure for 
hydrophobia. Another instance is that of Sticta pulmonaria, which acquired its 
familiar designations, " Oak Lung," and " Lungwort," as well as its specific name 
"Pulmonaria," either from its supposed efficacy in all pulmonary diseases, as a nutrient 
demulcent, or tonic, or from a fancied resemblance between the reticulate-pitted 
thallus to the structure of the lungs. However its name may have originated, 
it was for a long time regarded, not merely as a speedy cure for such diseases as 
ulcers of the Lungs, consumption, spitting of blood, etc., but was used both as a 
tonic and astringent in a great variety of other complaints. As an external appli- 
cation for wounds, it was considered very beneficial. Allusion has already been 
made to its frequent use as a nutrient in the form of jellies or diet-drinks by inva- 
lids generally. In Sweden it was no unusual circumstance for the peasantry to 
give it to their cattle, but more particularly the sheep, in epidemic catarrh ; whilst 
in Germany it was mixed with salt, and given to the cattle for similai- purposes. 
The virtues of the plant, are, however, generally believed to have been more imag- 
inary than real, writers on the subject generally ascribing their origin to the already 
alluded to fancied resemblance between its thallus and the lungs. I now come to 
consider the last, but certainly the most important division of the subject, viz., the 
