BAST-FIBRES. 87 



275. Xyloses. If a cell still growing is in contact with a duct 

 at one or more of its perforations, the cell may intrude into the 

 cavity of the duct, and to a considerable extent. Such intrusive 

 growths are known as Tyloses (German, Thvllen). 



If the intrusive portion of the tylosis further multiplies, pro- 

 ducing new cells, the cavit\- of the duct ma}- contain a confused 

 mass of irregular cells of various shapes and sizes. Such masses 

 are often found in the ducts of Quercus alba, Q. castanea, Q. ma- 

 crocarpa, Q. tinctoria, Q. virens, Castanea vesca, Carya alba, 

 C. olivaeformis, C. amara, Juglans nigra, Sassafras officinalis, 

 Morus rubra, Maclura aurantiaca, and Robinia Pseudacacia. In 

 the latter they are especially striking. 1 



BAST-FIBRES (LIBER-FIBRES). 

 (Sclerenchyma of many recent German authors.) 



276. The name bast was originally given to the inner bark of 

 the linden (bass-wood), and hence originated its use as a prefix 

 in " bast-matting," etc. ; the name liber was applied in a more 

 general way. namely, to any smooth inner bark (upon which one 

 could write). That which imparts strength to inner bark, mak- 

 ing it of use in the arts, consists of long and tough cells with 

 very much reduced calibre ; but these are not confined by any 

 means to inner hark. Owing to this fact, some have thought best 

 to abandon the terms bast and liber for such cells, and adopt, 

 on account of their firmness, a term formerl}- given to grit-cells, 

 namely, sclerenchyma ; the older terms, however, arc not likely 

 to lead to confusion, whereas the other might. It is in the bark 

 of dicotyledons that liber-cells or liber-fibres occur most abun- 

 dantly. 



Their prevailing shape is that of a slender spindle, which may 

 taper simply, or may be somewhat forked at the extremity. 



The following can be seen only under a lens : 



Euonymus Europaeus 20 /*. 



Fagus sp. . 28 " 



Crataegus sp 30 " 



Ligustrum sp 35 " 



Pyrus communis 40 ' 



1 Mr. P. H. Dudley, who communicates some of the names in this list, adds 

 in his note : " So far I have never found any tyloses in ducts with scalariform 

 markings. " 



