200 Macfarlane—Current Problems 
for experimental work. I may 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 varying 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. fava. 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 S. purpurea, When such are removed and experi- 
