102 — 
wise, the heights of the lamellae vary. Again, the lamellae of immature 
leaves differ from those of mature ones. The leaves and lamellae of new shoots 
differ from those of the old shoots when the amount of humidity or soil mois- 
ture is altered. This can easily be shown experimentally by transferring a 
plant from a moderately dry situation to a dish of water under a bell jar and 
later comparing the leaves of the new shoots with those of the old. The 
thickness of the outer wall of the end cell is also a variable quantity. In 
fact it is quite evident that certain external factors (climatic and edaphic as 
well as physiographic) play no small part in determining the form and struc- 
ture of the lamellae, the leaves, and even the whole plant. The query sug- 
gests itself, “Are these factors alone wholly responsible for the existence of 
any of the varieties which have received distinctive names?” Here is a 
good field for experimentation. 
Polytrichum formosum was reported from various New England states 
prior to 1885. Undoubtedly the bulk of the material so reported must be 
referred to P. Ohioense as has been repeatedly shown in various articles and 
catalogues since the date mentioned. 
Polytrichum gracile was reported from Massachusetts and New Hamp- 
shire in 1847 by William Oakes (Hovey’s Magazine, 13 : 174). Dr. A. J. 
Grout writes me that the only specimens of this species which he has were 
collected in Vermont, so the New Hampshire locality mentioned in Rhodora 
(1: 53) is undoubtedly an error. The Vermont plants were collected on both 
Willoughby Mt., and on Mt. Mansfield by Dr: G. G. Kennedy. 
Polytrichum Jensenii is a plant which is known from Lapland, Finland, 
Spitzbergen, Greenland, Alaska, and the Yellowstone Park. The Maine 
plant which is here referred to this species grew amongst sphagnum in a 
bog at Presque Isle. It differs mainly from authentic material, kindly loaned 
by Mr. J. M. Holzinger, in having longer and somewhat flexuous stems, less 
rigid leaves, and thinner-walled marginal cells of lamellae. 
Brown Univerity. 
DIE EUROPAEISCHEN TORFMOOSE. 
By G. Roth, Verlag von Wilhelm Engelman, Leipzig. 
Herr G. Roth, whose exhaustive work on the European mosses was ably 
reviewed by Prof. Holzinger in the pages of The Bryologist last year (Vol. 
viii, p. 1 13), has placed students of bryology under further obligations by the 
publication of his work on the European Sphagnaceae. This work consists 
of eighty pages of letter press with eight plates, uniform in size and method 
of reproduction with his “ Euro paeisc he Lciubmoose,” and it is published at 
the very moderate price of 3.20 marks. 
After an introduction, giving a concise account of the intimate structure 
of these remarkable plants, Herr Roth, in the systematic portion of his work, 
follows very largely the lines taken by Dr. C. Warnstorf, familiar to many 
English students, in Mr. S. C. Horrell’s “ European Sphagnaceae P and lately 
further amplified by Dr. Warnstorf himself, in his “ Leber und Torf moose 
der Mark Brandenburg .” 
