496 BIOGRAPHICAL SKETCHES. 
had visited him at Upsala, and he kept up a correspondence 
with him to the end of the venerable botanist’s life. He caught 
from Fries, or he developed independently, and cultivated te 
perfection, that sense of the value of the indefinable something 
which botanists inadequately express by the term ‘“ habit,” 
which often enables the systematist to. divine much further than 
he can perceive in the tracing of relationships. Upon this, in 
direct reference to Fries, and with a use of the term that seems 
to correlate it with “insight,” Tuckerman remarks : “So great 
is the value of Habit in minds fully qualified to apprehend and 
appreciate its subtleties, that such minds may not only antici- 
pate what the microscope is to reveal, but help us to under- 
stand its revelations.” It should be remembered, however, 
that when Fries did the best of his work there were no micro- 
scopes of much account ; and it is probable that Tuckerman 
would have done more, and perhaps have reached some differ- 
ent conclusions, if he had earlier and more largely used the 
best instrumental appliances of the time. One advantage, how- 
ever, of his way of study, and his philosophical conception of 
an ideal connection of forms which are.capable of a wide play 
of variation, was that he took broad views of genera and spe- 
cies. So he was quite unlike that numerous race of special- 
ists who, in place of characterizing species, describe specimens, 
and to whom “ genus” means the lowest recognizable group 
of species. 
As to the vexed question in Lichenology, which came to 
him rather late and seemed to threaten the stability of his 
work, it was most natural that, at his time of life, he did not 
take kindly to the Algo-fungal notion of Lichens, and that he 
was convinced of its falsity by questionable evidence. 
Professor Tuckerman was much more than an excellent spe- 
cialist. Happily, he did not become such until he had laid a 
good foundation, for the time, in general systematic botany ; 
and his early studies show that he was a man of scholarly cul- 
ture over an unusually wide range. He was at home in the 
leading modern languages ; he wrote Latin with reasonable 
facility, and botanical Latin remarkably well; he had given 
serious attention to law, divinity, philosophy, and history ; and 
