BAST-FIBRES. 87 



275. Tyloses. 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 



v- 



growths are known as Tyloses (German, Thy lien). 



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

 ducing new cells, the cavit\- of the duct may 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, Gary a alba, 

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

 Morns 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 

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



/ / / 



means to inner bark. 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 formerly given to grit-cells, 

 namely, sclerenchyma ; the older terms, however, are 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 Europseus 20 fj.. 



Fagus sp 28 " 



Crataegus sp 30 " 



Ligustrum sp. . . . . 33 " 



Pyrus communis 40 " 



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." 



