— 2 — 
sacrifice is involved in such a task will be appreciated by those who have 
attempted a similar one even though upon a smaller scale, in some field of 
taxonomic study. This work brought Tuckerman a knowledge of lichen 
species possessed by very few even of the European lichenists, and cul- 
minated in his two great contributions to North American lichenology, the 
“ Genera Lichenum ” in 1872 and the “Synopsis,” the first volume of which 
appeared in 1882 and the second in 1888. Of these two great works, we may 
venture a few words. The author was conservative in his view of genera 
and species and seemed to have followed Fries very largely in his classifica- 
tion of the American lichens. His views as to system of classification and 
as to generic and specific limitations can scarcely be expected to endure in 
all particulars. Yet his conservatism was by no means a fault, and has no 
doubt greatly aided in the study of lichens. 
Tuckerman was to lichenology what Asa Gray was to the study of our 
seed-plants, and we cannot pay too high a tribute to the labors of these two 
men. Tuckerman's contributions to North American lichenology consist of 
forty-eight titles, but the number by no means measures the amount of work 
involved, for he aided others continually and much of his labor received no 
public recognition. Conservative as he was, his new species and varieties 
numbered some three hundred and sixty-five, about two hundred and fifty 
of these being found on the North American continent, some sixty of the 
remainder on the island of Cuba, and nearly an equal number from various 
parts of the world and not to be regarded as North American. Including the 
Cuban lichens named by Tuckerman, the number of species and varieties 
described in the two volumes of the “Synopsis” for North America, is 
approximately one thousand and fifty, and this number is no doubt consid- 
erably below the whole number of North American lichens known by Tuck- 
erman. 
Tuckerman was pre-eminently a systematist, but some words are in 
order regarding his views on some other questions of lichenology. In regard 
to the theory of Schwendener as to the dual nature of lichens, he was more 
guarded in his statements than many of the other systematic lichenists of 
his day. While he readily admitted that there were some arguments in favor 
of the theory, he seems finally to have adopted the views of Minks, and like 
Muller and some others of his day, thought that he had himself demonstrated 
the existence of the “ microgonidia.” This he regarded as establishing a 
boundary line between lichens and fungi. It is pleasant to note, however, 
that during the years of sharp debate, Tuckerman was always careful and 
•considerate in his treatment of the question. It is also quite as pleasant a 
task to record that in a short paper entitled, “ Can Lichens be Identified by 
Chemical Tests,” Tuckerman remarks that his own observations have led 
him to believe that such tests are scarcely reliable, a view which doubtless 
meets the approval of later lichenists generally, since we have reached 
more definite knowledge regarding the anatomy of these plants. 
Excellent memoirs of Tuckerman by Willey, Gray and Farlow give much 
more detail than can be incorporated here. Grinnell, Iowa. 
