20 



BULLETIN 474, U. S. DEPARTMENT OF AGRICULTURE. 



vessel is in contact with wood-parenchyma fibers, and in horizontal 

 rows where it is in contact with pith rays, often giving the vessel 

 a scalariform (ladder-like) appearance. The majority of vessels 

 contain reddish-brown tyloses. These masses occur at regular inter- 



C 



/ B 



Fig. 4, A. — a, a, Two segments of a vessel, and b, wood-parenchyma fiber, both separated 

 from tbe wood of Swictenia maliarjoni ; c, shows complete absorption of the partition 

 walls of each vessel segment; d, small bordered pits. Magnified about 100 diameters. 



Pig. 4, B. — Wood fiber( separated) of Swictenia mahagoni, showing cross-partitions at a. 

 Magnified about 100 diameters. 



vals (longitudinal section), and often appear as minute partition 

 walls within the vessels. They stain very readily with hrematoxylin 

 and dissolve under the action of Schultze's maceration mixture and 



