Rate of Growth and Ecesis in Lichens 145 



varied from 2 to 30 mm. across. At this time the study differed 

 in appearance from the surrounding undisturbed area only in that 

 the areas of thallus were more scattered. 



Kentucky, area 4a, habitat like Kentucky, area 4. 6 All the 

 apothecia of Biatorella simplex were taken from a quadrat 5 cm. 

 square, using the hand lens to get the smallest ones and taking 

 also a large proportion of the epilithic parts of the thallus. 

 After 4 years the quadrat showed numerous apothecia, some of 

 which were 1.5 to 2 mm. in diameter. 



Kentucky, area 21, on the flat top of a sandstone block near 

 the top of a high, dry hill, the block 1 by 1.4 m., 1.3 m. high, 

 and lying in the sun for 4 or 5 hours near the middle of the day, 

 but shaded during the remainder of the day by a high cliff on one 

 side and by trees on another. A quadrat of Ramalina calicaris 

 was laid out 1.5 cm. square, and the Ramalinae were all removed, 

 except basal remnants about 0.1 mm. long. After 10 months 

 several plants were found that showed no evidence of having 

 been cut off, varying in size from those too small to be seen with- 

 out the hand lens to others 0.1 to 0.2 mm. long. After 8 years 

 there were 6 plants from 2 to 5 mm. long, all sterile. 



Kentucky, area 27, at the edge of a high, dry cliff facing north- 

 ward, partially shaded in the forenoon by shrubs to the south. 

 The center of a thallus of Parmelia conspersa 28 by 33 cm. was 

 taken out over an area 20 by 25 cm. across, except small frag- 

 ments not easily detached from the rock. Ten areas 1 to 2.5 cm. 

 across and many other minute areas were left. After 10 months 

 the marginal zone of the thallus had grown outward until the dis- 

 tance from one side of the margin to the opposite side was 29 and 

 34 cm. in the two directions in which the thallus had been measured 

 previously. The inner border of the marginal zone left undis- 

 turbed showed numerous lobes regenerated and extending inward, 

 these lobes varying in length from 1 to 15 mm. The areas left in 

 the denuded center showed regenerated lobes about their margins, 

 varying in length from those barely visible under the hand lens to 

 others 3 mm. long. Also there were many minute thalli arising 

 over the denuded center, varying in size from those only discern- 

 ible by aid of the hand lens to others from 0.5 to 1 mm. across. 



6 See Kentucky, area 4, p. 151. 



