SCIENCE 



and Zygophyllaceae. Various writers 1 have 

 called attention to this feature which is espe- 

 cially striking on red sanders (Pterocarpus 

 santalinus L. f.), narra (P. indicus Willd.), and 

 Jamaica quassia (Picrasma excelsa Planch.). 

 Von Hohnel (loc. cit.) observed it in about 80 

 different woods, all tropical or sub-tropical but 

 one (Diospyros virginiana L.), and most of 

 them unidentified. His list of the identified 

 woods includes 35 genera of 12 families, viz., 

 Ca3salpiniacea3, Papilionaceae, Mimosaceae, 

 Zygophyllaceae, Biittnereaceae, Malvaceae, Ced- 

 relaceae, Bignoniaceae, Simarubaceae, Ebenaceae, 

 Rosaceae and Sapindaceae. 



Included in v. HohneFs list are two species 

 which occur in the United States, viz., 

 Swietenia mahagoni and Diospyros virgin- 

 iana. In addition to these two the present 

 writer has observed tier-like arrangement in 

 the woods of JEsculus octandra, Tilia ameri- 

 cana, T. pubescens, T. heterophylla Vent, and 

 Ouaiacum sanctum. 



.ESCULUS (BUCKEYE) 



In the wood of JEsculus octandra the rays 

 are fine, uniseriate, uniform, inconspicuous, 

 mostly 10-12 cells high, measuring about 0.25 

 mm. The average distance between the rays 

 is, vertically, 0.15 m.; laterally, 0.06 mm. 

 Their arrangement is in horizontal series, 

 very regular on the radial section but form- 

 ing somewhat wavy lines on the tangential, 

 though always plainly visible to the unaided 

 eye. The vessel segments are from 0.35 to 

 0.40 mm. long and are in series, the horizontal 

 planes of their perforations alternating with 

 the rays. The fibers appear not to be in 

 storied arrangement. 



The cross-markings on tangential surface 

 are characteristic of A. octandra and were 

 not observed in A. glalra Willd., A. cali- 



2 Fliickinger, J. A., " Pharmacognosie der 

 Pflanzen," 2d ed., pp. 463, 466. Wigand, A., 

 ' ' Anatomische Atlas zur pharmaceutischem Werk- 

 ende," 1865, tables 26, 27. WMtford, H. N., 

 "The Forests of the Philippines/' Bui. 10, Bu- 

 reau of Forestry, Manila, P. L, 1911, Vol. II., p. 

 36. 



fornica Nutt. or A. hippocastanum L., though 

 all three show indistinctly on radial surface a 

 tier-like arrangement of the wood elements. 

 This feature is thus important in separating 

 the wood of A. octandra from others of the 

 genus. 



TILIA (BASSWOOD) 



Tier-like arrangement of the wood elements 

 is characteristic of the woods of Tilia ameri- 

 cana } T. pubescens and T. heterophylla. The 

 ending of the vessel segments, wood fibers and 

 wood parenchyma fibers is quite uniform. 

 The rays are widely variable in size and are 

 irregularly spaced. The small rays are uni- 

 seriate and mostly 10-15 cells high; the larg- 

 est are 3-5 cells wide and 50-100 cells high. 

 The cells are small and much flattened later- 

 ally. 



The cross-markings of Tilia are not con- 

 spicuous, but in proper light are usually 

 readily visible to the unaided eye. The aver- 

 age height of the tiers is about 0.40 mm. 



SWIETENIA (MAHOGANY) 



Tier-like arrangement is often characteristic 

 of the true mahogany (Swietenia mahagoni}. 

 While it may be absent, it is quite often very 

 conspicuous. When present the tiers vary in 

 height from 0.35 to 0.50 mm. The rays are 

 deep crimson in color, fusiform, and quite 

 irregular in size; 1-5, mostly 2 or 3, cells wide, 

 and 4^20, mostly 10-15, cells high. When 

 the rays are in storied arrangement they coin- 

 cide with the vessel segments. 



Swietenia senegalensis Deso. is said by von 

 Hohnel (loc. cit.) to be without cross-striping. 



DIOSPYROS (PERSIMMON) 



In Diospyros virginiana the rays are very 

 numerous, composed of large cells in 1-2 

 (rarely 3) rows, and from 2-14, usually 10- 

 12, cells high. They are arranged in hori- 

 zontal series which correspond with the ves- 

 sel segments, wood fibers and wood-paren- 

 chyma fibers. The arrangement is often 

 somewhat irregular and is never conspicuous, 

 though clearly visible to the unaided eye. 

 The height of the tiers is about 0.35 mm. 



