eps ) 
Day.] 338 {Dee, 21, 
of ducts and great size of medullary ray characteristic of this wood. 
Below it is placed a transverse section of Tulip-Poplar (same amplifica- 
tion), a wood which splits as easily as Pine. In it the abundance of ducts 
and weakness of medullary rays are shown. Plate IV gives the same 
woods, with the same amplification in tangential section, thus cutting the 
rays transversely and showing the contortion of the fibres in Buttonwood 
and their straightness in Tulip-Poplar. 
To Dr. J. T. Rothrock, for his kind assistance and advice during the 
preparation of the present article, the writer wishes to express his sincerest, 
thanks. Thanks are also due to Mr. Simmonds, of the University, for 
his careful preparation of the specimens tested, and to Messrs. Riehlé 
Bros., upon whose machines the work of testing was performed. 
EXPLANATION OF ILLUSTRATIONS. 
The drawings were all made by the aid of the camera lucida, 
In Plate II the amplification is 75 Ciameters. 
In Plate I, IIL and LV the amplification is 125 diameters. 
Plate I, a, Ulmus racemosa. (Good.) 
b, Ulmus racemosa. (Bad. ) 
Plate II, a, Pinus (sp. 2) 
b, Abies Ounadensis. 
6, Pinus Strobus. 
Plate III, a, Platanus occidentalis, ) : ( 
ae eh ti . Transverse sections, 
b, Liriodendron Tulipifera, | 
Plate IV, a, Platanus occidentalis, ) A fi ( 
nit eve ae langential sections 
b, Liriodendron Tulipifera, § 
In all the illustrations the following lettering is used ; 
W F—Woody Fibre. 
D—Duct. 
M R—Medullary Ray. 
