STONE: CONTACT STIMULATION 



467 



Table 12 



Showing Growth of Peas (Pisum sativum L.) in Contact with Excelsior. Average of 



Two Experiments with Eighty-two Plants^^ 



Average Height of Plants (Centimeters) 

 Percentage Gain 

 Stems by Contact 



Normal 13-07 



Contact excelsior 16.66 2j% 



Table 13 



Showing Growth of Cucumbers (Hypocotyls) {Cucumis sativus L.) in Contact with Ex- 

 celsior^^ 



Aveiage Height of Hypocotyl (Centimeters) 

 Percentage Gain 

 Hypocotyls by Contact 



Normal 15-04 



Contact excelsior 16.30 8.3% 



were to a more or less extent protected from light by the excelsior. 

 One of the experiments with lupines which was carried on at the same 

 time behaved in a similar manner to that of corn. In one case 31 out 

 of 36 of the normal plants developed leaves averaging 7 cm. in length 

 while none developed in any of the excelsior contact plants — a feature 

 due to the same cause, namely, to a brief and accidental exposure of 

 the plants to light. 



Table 14 



Showing Groivth of Cotyledons and Leaves of Corn (Zea Mays L.) in Contact with Ex- 

 celsior. Average of Two Experiments with 72 Plants'^ 



Table 15 



Showing Growth of Turnip {Hypocotyls) {Brassica Rapa L.) in Contact with Excelsior. 

 Average of Tzvo Experiments with IQ4 Plants^^ 



Average Height of Hypocotyls (Centimeters) 

 Percentage Gain 

 Hypocotyls by Contact 



Normal 8.57 



Contact excelsior 9.66 1 1 % 



^^ Experiments in which light was excluded. 



1^ Experiments in which light was excluded. No. of plants used 26. 



" Experiments in which light was excluded. 



'^ Experiments in which light was excluded. 



