144 



Mycologia 



2.7 cm. and 1.9 cm across respectively. After 1 year the Physcia 

 was 2.75 by 3.1 cm. and the Parmeiia 2.65 cm. across. After 2 

 years the Physcia was nearly circular and 3.6 cm. across, and the 

 Parmeiia was 3.5 cm. across. After 3 years the Physcia was 3.7 

 by 4 cm. and the Parmeiia 4.3 by 4.7 cm. across. An area 0.5 cm. 

 across near the center of the Parmeiia had disappeared. After 5 

 years the Physcia was 4 by 4.45 cm. and the Parmeiia 6 by 6.5 cm. 

 across. After 7 years the Physica was 5. cm. and the Parmeiia 

 9.5 by 10.4 cm. across. At 5 years the lost area of the Parmeiia 

 had increased to 1 cm. across, but at 7 years it was completely 

 regenerated. Both plants were sterile throughout the time of 

 observation. 



Ohio, area 16, on the trunk of a beech tree 20 cm. in diameter, 

 standing in a low, shaded wood. An area of Amphiloma lanu- 

 ginosum 3.3 by 4.1 cm. across was marked. After 1 year the 

 area had increased in size to 3.47 by 4.4 cm., but did not look 

 thrifty. The area was found to be in a dying condition at the 

 time of the next observation. 



Kentucky, area 10, on a sandstone block 28 by 35 cm., and 10 

 cm. high, lying in a high, dry, open wood. Fourteen areas of 

 Verrucaria muralis were marked, the largest 2.12 by 2.4 cm. 

 across, the others averaging from 0.4 to 0.5 cm. across in various 

 directions. After 10 months the largest plant was 2.2 by 3 cm. 

 across, and the others averaged from 0.5 to 0.9 cm. across in 

 various directions. The boulder disappeared before the time for 

 the next series of observations. 



Secondary Successions 



Kentucky, area ja, habitat like Kentucky, areas 6 and 7. 5 The 

 thallus of Amphiloma lanuginosum was scraped from the rock 

 over a circular area 10 cm. in diameter until no remnants were 

 visible to the eye. The area about the study was left with the 

 thallus of the same plant undisturbed. After 10 months there 

 was no evidence of ecesis. After 4 years the thallus was return- 

 ing over numerous centers from 0.5 to 2 mm. across. After 8 

 years the returning areas covered about half of the study and 



5 See Kentucky, areas 6, p. 142, and 3, p. 142. 



