i9i 7] • DOUBT—ILLUMINATING GAS 221 





in the lenticels just above ground. The underground parts were 

 enlarged to three times their normal size. The cortical tissue was 

 white and spongy. The bark split longitudinally and dropped off. 

 Small tubercles developed on many roots. The xylem and phloem 

 appeared normal. These results with Hibiscus agree with those 

 of Harvey and Rose (6) . 



Lycopersicum esculentum. — One plant was treated 24 days and 

 given 20 liters of gas, while a second plant was treated 18 days and 

 given 20 liters of gas. After a few hours' treatment, the lower 

 leaves began to show the epinastic response, falling after 2 days. 

 Many more roots developed on the stem above ground than on the 

 control plant. Roots grew up out of the ground, probably due to 

 loss of geotropic sensitiveness. Tubercles occurred on the roots. 

 The control plants showed some tubercles, but the number was 

 greatly increased upon the treated plants. Nematodes were 



present in many of these tubercles. 



Poa pratensis. — One sod was treated 38 days and given 60 

 liters of gas; a second 25 days with 60 liters; a third 5 days with 

 40 liters; and a fourth 8 days with 40 liters. There was no response 

 in any case. 



Populus deltoides. — Treated 81 days and given 60 liters of gas, 

 the roots developed many small " tubercles," being swollen to 

 twice the normal size at these points. The tissue was soft and 

 spongy. The stem showed no visible effect above ground; below 

 ground it was swollen and rigid, 



Pyrus communis. — Treated 40 days and given 100 liters of gas, 

 there was no visible response above ground, but all underground 

 parts were swollen. Longitudinal cracks appeared, in which was 

 soft spongy tissue. All the roots were irregularly enlarged, all the 

 proliferation tissue being in the cortex (tig. 6) . 



Pyrus Malus. — Treated 62 days and given 160 liters of gas, the 

 response was very similar to that of the pear (fig. 6). 



Ricinus communis. — Treated 45 days and given 80 liters of 

 gas, all leaves except the youngest fell. The underground part 

 of the stem was swollen and cracked longitudinally. 



Salvia splendens. — One plant was treated 18 days and given 

 20 liters of gas, and another plant was treated 42 days and given 



