1882.] Botany. 395 



As microscopes become cheaper and less cumbersome, and as in- 

 formation as to the general structure of lichens becomes more 

 available, many students will turn their attention to these curious 

 products of the vegetable kingdom. Indeed, few of the thallo- 

 phytes recommend themselves in as many ways to the laboratory 

 worker as do the lichens. Their curious dual structure, their 

 colorless filaments (hyphas), contrasting strongly with the round- 

 ish green cells (gonidia). will alone furnish material for much 

 close observation, and if the student permits himself to inquire as 

 to the theories of Schwendener, and Minks, he need have no fears 

 of speedily exhausting the study. Then, too, the various forms 

 of fruiting, the differences in the spores and spore-sacs (asci) with 

 the development of the latter may well claim the prolonged at- 

 tention of the student. 



As a most important aid to the study of the lichens we have 

 now the first part of the long promised " Synopsis of the North 

 American Lichens," 1 from the hand of Professor Edward Tucker- 

 man, than whom no one is better able to write upon this subject. 

 Long ago (in 1848), Professor Tuckerman gave us a little book, 

 now rare, " A Synopsis of the Lichenes of New England, the 

 other Northern States, and British America," and in 1872 his 

 "Genera Lichenum; an Arrangement of the North American 

 Lichens." We now have Part 1 of what will doubtless be for 

 many years the standard manual of our lichens. The work being 

 the result of the author's life-long studies, we may reasonably look 

 for much of stability in the arrangement, and in the limits he has 

 assigned to species, genera, and other groupings. Indeed, we 

 notice but few changes in comparing this work with " Genera 

 Lichenum," and these are all of minor importance. 



The method of the book leaves nothing to be desired, the spe- 

 cific descriptions being full, and very carefully written. The separa- 

 tion of the species into tribes or sub-genera is equally well done, 

 and the student must be dull indeed who cannot readily follow 

 the author. The key to the arrangement, which precedes the de- 

 scriptive portion, includes all the genera of North American 

 hchens, seventy-two in number, while this part of the work treats 

 of but forty-three of these. 



It may be interesting to note what the author has to say upon 

 several questions which have been under discussion in botany. 

 As to their relationship we find (p. v), " The lowest divisions of 

 vegetable life may still be recognized as Algae, Lichenes, and 

 Fungi ; and conveniently associated together under the designa- 

 tion of Thallophytes ; * * * * and there is no doubt, not- 

 withstanding the' numerous and now startling discrepancies of 

 these vast groups, that they stand in close natural relations to 



Oadooiei, ind ■ \ . author ol Genera Lich- 



enum. rj t>stlJ11 . s _ K _ Cassino, Publisher. 1 882. 



