Jan. 1, 1806.] 



SCIENCE-GOSSIP. 



11 



and the difficulty would be greater to point out the 

 features which distinguish the produce of the mul- 

 berry worm from that of the Tussch of India, the 

 Moonga or Erie of Assam, and the Aiiaute of recent 

 introduction into Europe. 



Vegetable fibres of the cellular kind are hairs 

 which invest the seeds of certain plants, Cotton 

 being of the chief importance (fig. 11, a). This has 

 been described as a flat band with thickened margins, 

 and a delicate tracery down the centre ; much 

 twisted throughout its length. This may appear to 

 be the structure on a superficial examination of the 

 dried cotton, but the normal structure is certainly 

 that of a cylindrical hair with thin walls, readily 

 collapsing and twisting as it becomes dry, its ap- 

 parent margin being formed by incomplete compres- 

 sion and the resistance at the edges as seen in the 

 following section of a fresh ( fig. 12, a) and dried hair 

 (b). The supposed tracery is an optical illusion, 



Fig. 12. 



caused by the irregular wrinkling of the two oppo- 

 site walls when in contact. Very important investi- 

 gations on this subject have been commenced in 

 Manchester. Are there really any distinguishable 

 microscopic differences between Sea Island and 

 Egyptian, New Orleans and African, or between 

 Brazilian and Surat ? 



Vascular fibres are derived either from the inner 

 bark (liber) of exogenous or the vascular bundles 

 of the leaves of endogenous plants. Each of these 

 groups would possess their own peculiar features. 



Fig. 13. a. Flax ; b. Jute. 



The most important of liber-fibres is Elax, obtained 

 from the common flax plant (Lhmm usitatissiriwm) . 

 This possesses a variable market value according to 



country or climate of production. It is natural to 

 inquire whether the microscope can detect differences 

 between Irish and Belgian, or between Egyptian and 

 Spanish flax. In I860, Dr. Eorbes Watson com- 

 municated an important paper to the Society of 

 Arts, in which the microscopic character of vege- 

 table fibres received more attention than had ever 

 before been given to the subject, and since that 

 period nothing has been attempted in advance. The 

 woodcuts used to illustrate these observations were 

 prepared for that occasion, and have been kindly 

 placed at our disposal by Dr. Watson. The micro- 

 scopic characters we are about to give are those 

 which then accompanied the illustrations. 



The Jlct.c fibre (fig. 13, a) presents at varying dis- 

 tances certain characteristic cross markings, the 

 outlines of the fibres are hard and smooth, and the 

 ultimate fibiilke can seldom be detected until care- 

 fully detached from the ordinary fibres. 



A strong fibre is obtained from the Chinese nettle, 

 or Rhea, (see S. Gos., vol. i. p. 277), known botani- 

 cally as Bmhmeria nivea, and sometimes called 

 China-grass. Under the microscope its fibres present 

 a peculiarly rough appearance, and when viewed by 

 reflected light have an appearance not unlike frosted 

 grass. 



Another Indian nettle, called the Neilgherry 

 Nettle {Urtica lieterophylla), of which a figure has 

 already been given (vol. i. p. 270), yields a similar 

 but more woolly fibre. (Eig. 14, b.) Under the 



Fig. 14. a. Chinese nettle ; b. Neil gherry nettle ; c. Bedolee. 



microscope it exhibits considerably greater asperi- 

 ties than the Rhea, and has been recommended as a 

 substitute or for admixture with wool. A com- 

 parison of the two figures (fig. 11, b, and fig. 14, it) 

 will prove that such an admixture could readily 

 be detected. 



The fibre of the Mudar {Calotropis procera) is 

 similar in commercial value, but characteristically 



