SCIENCE 



The horizontal seriation of the rays appears 

 to have been first described by Molisch. 8 



Available specimens of the wood of D. tex- 

 ana Sch. do not exhibit the cross-markings. 



GUAIACUM (LIGNUM-VIT.E) 

 The wood of Guaiacum sanctum exhibits 

 very fine and quite uniform cross-markings, 

 visible with the aid of the lens. The rays are 

 very fine, uniseriate, mostly 5-7 cells high, 

 deeply colored, appearing under lens like fine 



* Molisch, H., " Vergleichende Anatomie des 

 Holzes der Ebenaceen und ihrer Verwandten, ' ' 

 Sitzungsberichte der Mathematische-Naturwissen- 

 scJiaftlichen Classe der Icaiserlichen AJcademie der 

 Wissenschaft, Vol. 80, Part I., Wien, 1879. 



hachures. The height of the tiers varies from 

 0.15 to 0.18 mm. The scattered vessels are 

 filled with a dark-colored resin which adds to 

 their prominence. The vessel segments alter- 

 nate with the rays. 



Guaiacum, officinale L. is similar to G. 

 sanctum in the arrangement of the wood ele- 

 ments. The distance between markings is 

 often as low as 0.11 mm. The rays are about 

 0.05 mm. apart laterally and 90 ^ vertically. 



In addition to those mentioned above, the 

 writer has observed many tropical woods 

 (particularly African and Brazilian) with 

 tier-like arrangement of their elements. 



SAMUEL J. KECORD 



YALE FOREST SCHOOL 



