﻿(58 MacDougal: A Contribution to 



or other support. The most advantageous position in general 

 would be when the organs are separated with their axis forming 

 an angle of 45 degrees, and the tips curved in any direction except 

 toward the other tendril. If the movements of the leaf should 

 brine: a branch between the arms of the Y thus formed, it will be 



enclosed in 50 to 80 seconds, 

 work of any climbing device. 



The Sensory Zone. 



The sensory zone apparently consists of the single layer of 

 epidermal cells. These cells, seen from the surface, exhibit the 

 greatest diameter tangentially, and seen in cross section the di- 

 ameters are nearly equal. The nucleus occupies a central posi- 

 tion, and the ectoplasmic layer on all sides is extremely thick and 

 very densely granular. It is of course impossible to discover the 

 condition of these elements in an unstimulated condition. 



The outward convexity of the external membranes would offer 

 most advantageous conditions for the appreciation of delicate 

 stimuli. The contiguity of the motor cortex cells with numerous 

 interprotoplastic connections would facilitate the transmission of 

 impulses. 



Mechanism of Curvature. 



The method of production of curvature was determined by 



mea 



and concave sides of curved tendrils and comparison of the same 

 with data obtained from straight organs. The measurement- of 

 one set are given below : 



Table I. 



Measurements of opposite sides of straight organs. 



Wm atOffCsUA LmWGTH. Average. \ember of Cj L, ngth. Average 



Epidermis 8 797 12. 1 Epidermis 9 100 II.I 



5 102 20.4 5 



100 20. 



4 6 100 i6 # 6 



(A) 4 104 26. 



Epidermis 10 100 



7 1 



6 



( B ( 4 



xo 



Epidermis 10 



M 3 



6 



15.6 



1 



*3-5 



4 



4 no 27. > 



ico 10 



9S 10. 



100 16.6 



98 24-5 



