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Thuidium microphyllum (Lindb.) Best. 
“ recognition B. & S. 
Sphagnum cymbifolium (Ehrh.) Hedw. 
“ squamosum Pers. 
“ acutifolium Ehrh. 
“ “ var. rubellum (Wils.) Russ. 
“ “ quinquefarinum Lindb. 
“ intermedium Hoffm. 
“ cuspidatum Ehrh. , Brooklyn, N. Y. 
LICHEN NOTES No. 3. 
“ Chemical Tests ” in Determining Lichens. 
G. K. Merrill. 
In 1866 the late Dr. William Nylander published the results of his experi- 
ments regarding the behavior of certain aqueous chemical solutions, when 
applied to the cortical and medullary layer of the lichen thallus. The chemi- 
cal menstrua found most effective and useful were potassium-hydrate and 
calcium hypochlorite, symbolized as KHO and CaCl. The results obtained 
hinged on a capacity of the solutions employed to produce a coloration on ap- 
plication to that portion of the thallus to be tested. Dr. Nylander claimed 
to have found that different lichen species were differently affected by the re- 
agent employed, but that individuals of one species were constant in the pro- 
duction of a given reaction. The object of the test was to assist “in not only 
the discrimination of many difficult and closely allied species, but also in 
associating varieties with their proper species, and in some instances in de- 
fining the affinities of genera.” 
The novelty of constituting botanical varieties on purely chemical grounds 
aroused antagonism at the time, which has persisted more or less to the pres- 
ent day, but the unquestionable value of the discovery as an aid in the de- 
termination of established species, made converts of nearly the whole body 
of European lichenists. Among those to negative the value of “chemical 
tests ” from the first, was the late Prof. Edward Tuckerman, and it is regret- 
fully stated that his views were adopted with great uniformity by the later 
American investigators. It will be of interest to quote from the published 
words of those Americans who have written on this topic. 
In the American Naturalist for April, 1868, Tuckerman first voiced the 
disapproval, and we will selectively quote from his paper. Under the cap- 
tion, “ Can Lichens be Identified by Chemical Tests?” he says: “ I have 
gone through a large part of my North American and exotic lichens in the 
light afforded by these (Nylander’s) experiments and found the facts, if 
sometimes suggestive of more than is stated, generally clear: much clearer 
than the value attributed to them. Is it not indeed safe to say at once that 
species are not determined in botany by such tests Y” “ The observations 
cited are however incomplete ; and derive from this not a little of their inter- 
