76 SELBY: STUDIES IN ETIOLATION 
Explanation of plates4and 5 
PLATE 4 
Persea gratissima 
Fic. 1. Portion of cross-section of middle of stem of normal plant. 
Fic. 2. Portion of cross-section of middle of stem of etiolated plant. 
Fics. 3, 4. Bract-like hairy leaves of etiolated plant, X 4% 
Fic. 5. Etiolated 10-weeks’ seedling (same as figure 7), after two months’ illumi- 
nation, about one-fifth natural size. 
{G. 6, Leaf of normal plant, about one-half natural size. 
Fic. 7. Etiolated 10-weeks’ seedling, about one fifth natural size. 
PLATE 5 
Luphorbia corollata 
Fic. 1. Portion of cross-section of stem of normal plant. 
Fic. 2. Portion of cross-section of stem of etiolated i 
Fic. 3. Leaf of normal plant, two thirds natural s 
Fics. 4, 5. Leaves of etiolated plant, & 114. 
Asclepias incarnata 
ay 6. Portion of cross-section of middle of stem of etiolated ee 
- 7. Portion of cross-section of middle of stem of normal 
soa 8. Portion of cross-section of concave side of curved stem ro etiolated plant. 
Fic, 9. Portion of cross-section of convex side of curved stem of etiolated plant. 
Fic. Io. Liat of etiolated plant, & 114. 
