TWO BOOKS ON LICHENS 279 



This notice may close with the following extract from a letter 

 of De Geer from Leufsta, dated October 16th, 1772 : — 



" A short time since my son [Emanuel] wrote to me from 

 London, that Solander dui-ing his voyage got over 1000 new plants, 

 as well as several packages of special animals in spirit. He thought 

 that the Archiater [Linne] should be invited to travel to London 

 without expense, to inspect and describe all these rarities. It 

 would be highly desirable if the Archiater's years would permit of 

 such a journey, as it would be of the greatest value to all lovers 

 of Nature, for no so eminent a judge exists in the world, as the 

 Archiater is." B D T 



Two Books on Lichens. 



The Lichens of Minnesota. By Bruce Fink. Pp. xvii, 269, 51 pi. 



18 figs. Washington, 1910. 

 Die Brandpihe der Schu-eiz. By Prof. Dr. H. C. Schellenberg. 

 Pp. xlv, 180, 79 figs. Price, 6 m. 40 pfg. Bern, 1911. 



Mr. Bruce Fink has been engaged for many years in the 

 study of Minnesota Lichens, both in the field and in the laboratory, 

 and papers embodying the results of his observations have appeared 

 from time to time in the Minnesota Botanical Studies and in the 

 Bryologist. The volume before us furnishes the complete record 

 of his work. 



A clear and succinct account is given in the Introduction of 

 Lichens in general, their morphology and physiology, their distri- 

 bution and economic uses. The principal part of the work is 

 systematic, and is prefaced by a descriptive catalogue or outline 

 of classification, largely based on accepted modern methods. The 

 different orders and families are described, and the catalogue is 

 followed by an artificial key to the genera, which should prove 

 helpful to students in determining the position of their plants in 

 the scheme of classification. With each genus is given a key to 

 the species. 



The author has successfully avoided too great technicality in 

 his diagnoses of species ; he claims merit for being the only writer 

 who gives size of thallus, podetia, &c., but when one turns to the 

 details and finds that certain podetia may be anything between 

 3 mm. and 30 mm. in height, or, as in another case, from 25 mm. 

 to 90 mm., one wonders where exactness comes in. The crusta- 

 ceous lichens are equally variable, and measure, say, 10 or 15 mm. 

 to 60 mm. in diameter. A form such as Lecanora tartarea, which 

 may spread for feet, if not for yards, is left unmeasured. The old 

 vague terms of "effuse," "widely spreading," &c., seem to fit the 

 requirements of lichens sufficiently well, though to beginners in 

 the study these measurements may be of assistance. 



Lichens have a wide distribution, many genera and species 

 occurring in all countries where similar conditions prevail, and 

 Minnesota Lichens, as the author surmises, should prove a useful 

 text-book for a wide region in North America from the Atlantic to 



