76 Selby: Studies in etiolation 



Explanation of plates 4 and. 5 



Plate 4 



Per sea gratis sima 



Fig. I. Portion of cross-section of middle of stem of normal plant. 

 Fig. 2. Portion of cross-section of middle of stem of etiolated plant. 



Figs. 3, 4. Bract-like hairy leaves of etiolated plant, X 4.K* 

 Fig. 5. Etiolated I o-weeks' seedling (same as figure 7), after two months' illumi- 

 nation, about one-fifth natural size. 



Fig. 6. Leaf of normal plant, about one-half natural size. 



Fig. 7. Etiolated io-weeks' seedling, about one-fifth natural size. 



Plate 5 



Euphorbia c or 1 lata 



Fig. I. Portion of cross-section of stem of normal plant. 

 Fig. 2. Portion of cross-section of stem of etiolated plant. 

 Fig. 3. Leaf of normal plant, two thirds natural size. 

 Figs. 4, 5. Leaves of etiolated plant, X l /i- 



Asclepias incarnata 



Fig. 6. Portion of cross-section of middle of stem of etiolated plant. 



Fig. 7- Portion of cross-section of middle of stem of normal plant. 



Fig. 8. Portion of cross-section of concave side of curved stem of etiolated plant, 



Fig. 9. Portion of cross-section of convex side of curved stem of etiolated plant. 



FlG, 10. Leaf of etiolated plant, X ll A- 



