STONE: CONTACT STIMULATION 



459 



Response of Plants to Contact Stimulation with Wires and 



Twine 



The investigations relating to the effects of contact with wires, etc., 

 are given in Tables 2-9. All of these experiments were made in a 

 well-lighted conservatory, the plants being grown in a good uniform 

 grade of loam either in solid beds or in benches. In this series 1-6 

 plants were enclosed by wires, or dowels, and twine, and in some 

 cases only fish netting was employed. The normal plants were in some 

 instances grown free from contact with one another and in others not. 

 In the case of only a single plant being surrounded by wire netting 

 contact would occur only with the wire, whereas when two or more 



Fig. 3. Showing growth of castor beans in contact and not in contact with 

 wire netting. Plants removed with as little disturbance as possible from original 

 position for photographic purpose. 



plants were grown tolerably close together they would eventually be 

 in contact with each other as well as with the wire netting, etc. Hence 

 contact stimulation would result not only from the use of wires, etc., 

 but from the contact of plants with one another, or in other words the 

 so-called normal plants were not in all instances free from contact, 

 inasmuch as when they were grown in groups they would eventually 

 touch one another and growth would be influenced. We therefore 

 have two series of experiments, namely: (a) those in which the 



