FERNS 29 



(Swedish Moss or Dyer's Moss) , a lichen of northern Europe. It may 

 also be prepared from the same lichens yielding orchil. The coloring 

 principle is apparently orcein. It is largely used as a coloring agent 

 for pharmaceutical preparations as well as in dyeing. The com- 

 mercial article varies considerably in tinctorial properties, this being 

 due to the crude methods of manufacture. 



Literature. Beringer, Proc. N. J. Pharm. Assoc., 1912; Arny, 

 Jour. A. Ph. A., 1913, p. 47; Gardner, Ibid., p. 51. 



LACMUS. Litmus. A dried extract obtained by the fermentation 

 of lichens yielding orcinol. The process of fermentation is similar 

 to that in the preparation of orchil and cudbear, but potassium car- 

 bonate is added and the time of fermentation is longer. When the 

 color of the solution is of the desired tint it is mixed with calcium 

 carbonate or gypsum, molded into small cubes and finally dried. 

 Most of the litmus is manufactured in Holland. 



The blue color of litmus is due to an amorphous brownish-red 

 substance known as azolitmin. It is a weak base which is soluble in 

 water and insoluble in alcohol. Commercial litmus contains several 

 other coloring principles. Litmus is chiefly used as an indicator of 

 neutrality in pharmaceutical and chemical work. 



ARCHEGONIATES 



FERNS AND FERN-ALLIES 



The Archegoniates, representing the highest group of Cryptogams, 

 include the Bryophytes and the Pteridophytes. The latter includes 

 the ferns and their allies, viz. : the horsetails and club mosses. From 

 a botanical viewpoint, as well as for economic reasons, it is one of the 

 most interesting groups of plants. The Pteridophytes are a very old 

 group, being first found in the Devonian and attaining their maximum 

 development in the Carboniferous age, during which time they 

 formed the bulk of the vegetation comprised in the coal-measures. 

 The forms existing upon the earth are still very numerous, comprising 

 about 5000 distinct species. The chief interest lies in their use as 

 ornamental plants. 



ASPIDIUM. Male Fern. The rhizome and stipes of Dryopteris 

 Filix mas and Dryopteris marginalis (Fam. Polypodiacceae), peren- 

 nials (Fig. 11), of which Dryopteris Filix mas is more widely distrib- 

 uted, being indigenous to Europe, Asia, North America, west of the 

 Rocky Mountains, and in the Andes of South America; while D. 

 marginalis is found in the Eastern and Central United States ancjl 



