130 PROCEEDINGS OF THE ACADEMY OF [1889. 



crossing points resistance is greatly increased, thus causing rapid 

 burning and destruction at such points. 



Such woods as Hickory and Rock-Elm furnish the very best of 

 our timbers. They are the toughest and most durable of our woods; 

 but they do not make good filaments. The medullary rays are 

 very numerous and the walls of the cells composing them greatly 

 thickened. The long, pointed, thick-walled wood-cells do not follow 

 a parallel course, but interlace with each other. This interlacing 

 of the cells gives to these woods their toughness. It is the main 

 characteristic also which renders them worthless when made into 

 electric filaments. Upon carbonization of such filaments the ten- 

 sion of the interlacing cells is relieved and the tissues composing it 

 become friable and easily fall apart. 



In the adult stem of the Bambusa a combination of anatomical 

 characters has brought about a result which makes it the most 

 fitting material so far as now known for the electric filament. 



The nearly parallel fibro-vascular bundles grow more numerous 

 as they approach the circumference of the stem and as is usual in 

 similar steins lose most, or sometimes all, of the woody elements, 

 thus becoming pure bast. The parenchymatic tissue which 

 toward the center of the stem may be composed of a layer of five 

 or six cells between the bundles, decreases in amount near the cir- 

 cumference until but one layer of cells remains. The walls of the 

 cells in this single layer often become so thickened, and at the same 

 time compressed by the growth of the bast, that these bundles appear 

 to make a solid zone of bast around the circumference of the stem. 

 The bast-cells also continue to thicken their walls until they 

 become, in the best specimens for the filament, completely filled and 

 solid. 



It is from this zone of bast at the circumference of the stem that 

 the filament is always taken. 



The following characters will be found to exist in such a filament: 

 Bast fibers solid ; very compact without inter-cellular spaces ; 

 nearly parallel ; joined together by mitred ends thus appearing as 

 continuous fibres; the presence of a minimum amount of paren- 

 chyma possible in such filament; a sufficient amount of cohe- 

 sion between the separate fibres to often cause the separation of 

 bast-cells in halves upon splitting the material. 



These characters secure the least possible diversification of cells, 

 i.e., the most homogeneous structure which can be secured where 

 long, solid fibers are sought. This filament is perhaps the nearest 

 approach, in its continuity of structure and uniform character, to 

 a metallic conductor of any tissue which can be found in the vegeta- 

 ble kingdom. 



The Botany of the Bahamas. — Prof. Charles S. Dolley 

 remarked that the list of Bahama plants which he presented for 

 publication this evening represents one hundred and fifteen families, 

 four hundred and ten genera, and six hundred and twenty-one species. 

 One-third of the families (forty-seven) are represented by but one 



