i8 



THE GUIDE TO NATURE 



To look at her is as fatal as to look 

 at the head of Medusa. It turns the 

 man of science to stone. I feel that I 

 am dissipated by so many observations. 

 I should be the magnet in the midst of 

 all this dust and filings." Thus he 

 showed that to study lichens seemed 

 to him the most complete dissipation 

 of a naturalist's interest. "I knock the 



his knowledge was meager — but that 

 he knew the varied morphological 

 types, included in the classification, is 

 perfectly clear. This entry in his 

 Spring Journal shows his recognition 

 of a fruticose, filamentous species, quite 

 the commonest of his Concord region. 

 "It is a rare lichen day. The usnea 

 [Usual florida (L.) Web.] with its large 



ROCK TRIPE. 

 ( Umbilicaria.) 



DOG LICHEN. 

 (Peltigera.) 



back of my hand against a rock," he 

 continues, "and as I smooth back the 

 skin I find myself prepared to study 

 lichens there. I look upon man but as 

 a fungus. I have almost a slight, dry 

 headache as the result of all this ob- 

 servation. How to observe is how lo 

 behave. Oh, for a little Lethe. To 

 crown all, lichens which are so thin are 

 described in the dry state, as they are 

 most commonly, not most truly seen. 

 They arc, indeed, dryly described." We 

 must smile here at Thoreau's premoni- 

 tion of the work of Edward Tucker- 

 man — the dullest of all botanical manu- 

 als. 



Of lichen species, as we have said, 



fruit is very rich on the maples in the 

 swamp, luxuriating in this moist, over- 

 cast, melting day, but it is impossible 

 to get it home in good condition." 



The Cladonias evidently attracted his 

 attention most frequently for I find 

 many allusions to them. There was 

 no season of the year that the little 

 Cladonia cristatella Tuck; a species later 

 to be named by Tuckerman, did not at- 

 tract his eve. "How swift," he writes, 

 ''Nature is to repair the damage that 

 man does! When he has cut down a 

 tree, and left only a white-topped and 

 bleeding stum]), she comes at once to 

 the rescue with her chemistry, and cov- 

 ers it decently with a first coat of gray, 



