152 



Mycologia 



nopsis schaereri, PI ac odium sideritis, Collema pustulatum, and 

 Physcia obscura (?) were growing on the upper surface of the 

 rock, from which the front one-fourth and the back one-fourth 

 were chipped 2 to 15 mm. deep. After 4 years many minute 

 primordia of lichen thalli were found under the hand lens, within 

 the chipped quadrats. After 8 years these quadrats were 

 sprinkled over with minute thalli of Pyrenopsis schaereri, a few 

 small thalli of Physcia obscura (?), and several minute and 

 sterile ones of Collema pustu ] atum. All of these thalli were 

 sterile ; but a single specimen of Placodium sideritis 1.5 cm. across 

 bore 4 minute apothecia. 



Ohio, area 7, on a limestone 65 by 5 cm. and 35 cm. high, stand- 

 ing nearly erect in a moist, shady wood, the quadrat covering half 

 of the 65 cm.-wide, nearly perpendicular rock face, chipped 4 to 

 18 mm. deep. After 2 years all of the chipped quadrat showed 

 an indistinct green coloration, in which the hand lens revealed 

 scattered areas turning toward the dark color characteristic of 

 Verrucaria nigrescens, which had covered most of the rock sur- 

 face before the quadrat was plotted. After 6 years this lichen 

 was found over more than half of the chipped quadrat with 

 numerous apothecia, and thallus nearly as dark as on surround- 

 ing undisturbed areas. 



Kentucky, area 7, habitat like Kentucky, area 6. 10 In an area 

 covered by Amphiloma lanuginosum, a circular portion 10 cm. in 

 diameter was chipped 1 to 10 mm. deep. After 4 years the 

 Amphiloma was found returning in patches averaging 0.5 to 2 

 mm. across in various directions and scattered over the whole 

 area. After 8 years the plant covered about three-fourths of the 

 surface, and a considerable number of larger patches ran from 

 5 to 10 mm. across in various directions. 



Ohio, area 8, from a levee 1.3 m. wide and 0.3 m. high, lying 

 9 m. from a brook, on usually dry ground exposed to the sun, the 

 limestone fragments composing the levee of sizes easily handled, 

 removed a portion 70 cm. long and replaced it by similar lime- 

 stone fragments taken from the bed of the brook and devoid of 

 plant growth that could be detected. After 3 years thalli of 

 Endocarpon pusillum 0.2 to 2 mm. across were found in con- 



10 See Kentucky, area 6, p. 142. 



