CONTENTS. 
Page. 
Tue Licnens or Minnesota. By Bruce Fink...............-------------- 1 
" Introduction..........-.--0 2-02 e eee cee ee ee cee ee eee cece eee eee ee ee 1 
Basis and aims of the present work.......-....----------+++------- _ 1 
Special bibliography.........-------------2+---e-e eee wee eeeeeeeeee 4 
Preliminary account of lichens... .. wee ee ee eee eee cece cece eee ee eeee 5 
Views as to their origin and nature...........-..-----.---------- 5 
Disposition of lichens adopted in this work.....-----.-.---------- 8 
The fungal symbionts and their related fungi......----.---.------ 8 
The algal symbionts and their related algee.........-..---.------ 9 
Gross morphology.....-...-.--------- 202 - cece eee eee e eee eee 10 
The thallus.........-.-....-.--------------- ee eee ee ee eee 10 
_ General forms of thalli........-..-...+--+---+-+---+-+++25+- 10 
Sizes of thalli.......-....--- 22-220 eee eee ee eee ee ee eee 11 
Surfaces of thalli..........-.--2---2.0- 2.222 - eee eee eee eee eee 11 
Colors of thalli.............2 02.2220 eee eee eee ee eee eee eee ee 12 
The apothecium...........-.--0-0--e eee eee cece eee eee es 13 
The disk.........0...ceece eee eee eee ce eee eee eee eee eeeeeee 13 
The exciple............ 2-2-0222 e ee eee eee eee eee eee eee eee 14 
Position of the apothecia................-------+-------+--- 14 
Stipes and podetia.........-..------2--- eee eee eee eee eee 15 
Rhizoids and cilia.......... 15 
Other structures.........-...-----22 22-2 eee ee eee eee eee eee ee 15 
Minute morphology.........--------- +20 eee eee eee eee rece eee 16 
Foliose thalli................2- 222-20 eee eee eee ee eee eee 16 
Crustose thalli...............---------------- eee eee eee ee eee 17 
Fruticose thalli...........------------ 2-222 eee eee eee eee 17 
The dermis..........------------- 2-2 - ee eee eee eee 18 
The upper corteX......-..-------2- 0-0-2 e eee eee eee eee 18 
The algal layer..........-..----------+-+-----+--- +++ aeeeeee 19 
The medullary layer............-------- +--+ 22-22 e eee eee eee 20 
The lower corteX.........------ 2000-022 e ee ee ee ee ee eee eee 20 
Soredia and spermagonia.........-..-----+------++++-- +--+: 21 
Cephalodia..........-.-.-----------+----++-- ween et cceeesecs 21 
Cyphellee. .......-... eee eee eee eee eee eee eee tee eeeee 22 
Breathing pores..........-------------+ 22 cece e eee eee eee 22 
Growth of thalli............-------2----------2-0e-e eee eee 22 
The apothecium in general..........-----------+--+-----+--- 24 
The epithecium............2.2---- 2-0-2222 e eee eee terres 24 
The hymenium..........--------+------++ 2-2-2222 e eee reece 24 
The thalloid exciple......2...------------ +--+ 22222 e eee eee 24 
The proper exciple........------- +--+ -++- e222 eee e eee eee 25 
The hypothecium........-.-.-------+---++--++ee eee eee eee 26 
The amphithecium...........-.----------2-e-e+e ee sere eee 26 
