SPHAGNUM MOSS NICHOLS. 229 



stringy forms, or forms with stiff or brittle stems or harsh texture, 

 must be avoided. 



The qualifications specified above are fulfilled in varying degree 

 by different members of the Oymbifolium group. In eastern North 

 America, Sphagnum papillosum (pi. 1), to a greater degree than 

 any other species, exhibits the requisite absorbency, softness, and 

 strength and is genera lty regarded as being much more satisfactory 

 for use in surgical dressings than any other form. Locally, under 

 exceptional conditions of growth, S. palustre, S. magellanicum, or 

 S. imbricatum — especially S. palustre — may compare very favor- 

 ably with S. papillosum, but as a rule these tend to develop too much 

 stem in proportion to foliage or have too harsh a texture to make 

 ideal surgical material. In the humid climate of the Pacific North- 

 west, however, S. palustre appears to develop even more luxuriantly 

 than S. papillosum and is there regarded as the most desirable 

 species. 1 



In the field, S. papillosum can usually be distinguished by its very 

 robust habit and its coppery to brownish color; it is never red or 

 purple. The other three species ordinarily are less robust. S. 

 palustre commonly is' pale greenish white in color; S. magellanicum, 

 pink or purplish red; S. imbricatum green or frequently tinged with 

 brown. These color distinctions are most pronounced in plants ex- 

 posed to the open sunlight; when growing in the shade all four 

 species are usually green. 



In this connection it should be emphasized, not only that different 

 varieties of sphagnum exhibit a wide range of variation when it 

 comes to their capacity for absorbing liquids, as well as in other 

 features which adapt them to surgical use, but also that the very same 

 species may vary greatly in different localities. Growing under 

 certain conditions it may acquire that soft, "bushy" habit so desir- 

 able in material which is to be used for surgical dressings, while 

 growing under other conditions it will be harsh, stringy, and quite 

 unfit for surgical purposes. Even Sphagnum papillosum exhibits 

 considerable variation in this respect. 



GEOGRAPHIC DISTRIBUTION OF SURGICAL SPHAGNUM. 



The genus Sphagnum is cosmopolitan in its distribution, and all 

 of the species which have been mentioned as being of surgical value 

 are widely distributed in Eurasia, as well as on this continent. In 



1 Mention might also be made here of tf. compactum which, when well developed, 

 would appear to he even hetter adapted to surgical work than the forms more gen- 

 erally recommended. This species possesses an unusually soft texture and exhibits a 

 remarkably high capacity for absorbing liquids. Unfortunately, while very widely 

 distributed, it is only occasionally that it is found in sufficient abundance and luxuri- 

 ance to be of practical value. 



136650°— 20- 16 



