Red ^Voo(l in Conifers. 



115 



Sununary oj Preceding Results. 



The stems were bent in curves. The white wood side was 

 under tension, and was the more strongly illuminated side. 



PiNUS STROBU8. 



Thickxess of Walls 

 Red Wood White Wood 



Internal Diamet?:k 

 Ked Wood White Wood 



On August 1 6th 1907, the lateral branches which had been 

 covered with tinfoil wei'e examined. .^ layer of red wood was 

 observed on the under side of the branches which had been 

 covered with tinfoil, as before. Hence Sonntag is incorrect in 

 supposing that heliotropic or pressure stimuli are responsible for 

 the formation of redwood. Sections of the lateral bi'anches 

 which were covered were cut, and the thickness of the trache- 

 ide walls and their inteiiial diameters were measured. 



EAperiiiicuiaJ Results. 

 Taxus baccata. 



Section I. 



Red Wood 

 Internal Diameter Thickness of Wall 



White Wood 

 Internal Diameter Thickness of Wall 



.010 mm. 

 .008 ,. 

 .009 ,, 

 .009 ,, 

 Average 

 .009 mm. 



.001 mm. 

 .002 ,. 

 004 .. 

 .004 ,. 



Average 

 .003 mm. 



.008 mm. 

 .005 ,, 

 .007 „ 

 .006 ,, 

 Average 

 .006 mm. 



.005 mm. 

 .002 ,, 

 .002 ,, 

 .003 ,, 



Average 

 .003 mm. 



