200 Macfaidauc — Curve ni Problems 



for experimental work. I ma\- be pardoned if I refer to a few 

 which have come under my personal observation. Experi- 

 ments performed by Dr. Schively on fruits of the hog peanut 

 conclusively prove that strong lignification of the cells after a 

 definite pattern will take place in two distinct zones of the 

 carpels when the fruits are exposed to the air, while the same 

 cells will remain thin and delicate if retained in moist soil. 

 Whether moisture alone, or moisture and darkness combined, 

 produces this effect has not yet been determined. 



Several years ago my attention was arrested by the appar- 

 ent varj'ing behavior of our native Sarracenias to varying 

 degrees of illumination. When the common species — S. 

 purpurea — grows under full exposure to the sun's rays, it is 

 of a deep crimson color. This is due to the presence of a 

 crimson pigment in the sap of the epidermal cells. When 

 slightly shaded by low herbage in an otherwise open situation, 

 it is crimson green, but lined along the veins with a deep 

 purple color. When shaded by shrubbery for several hours 

 daily it is green, streaked by narrow purple lines, and finally, 

 when under a continuous shade, it is uniformly green. By 

 removing plants of each of these to situations where the 

 degree of illumination can be adjusted, I have proved that 

 pigment production is a latent, or feebly expressed, or well 

 developed quality of the epidermal cells, according to the 

 intensity of environmental light stimuli. Even more interest- 

 ing is our common southern species, S.flava. It is nearly 

 always of a bright green or a yellowish green color in its 

 pitchers, though about half the individuals of a meadow will 

 show a few rich crimson lines along the back of the throat. 

 The latter when grown during successive seasons in shaded 

 situations will develop only green pitchers. But rarely over 

 wide stretches of territory in South Carolina and Georgia, 

 specimens may be gathered that are as richly colored as the 

 finest of 5. purpurea. When such are removed and experi- 



