190 Dr. Meyen on the Formation of the Tubes of the LAber, 



scription and figures of that species in the Annals of the Ent. 

 Soc. Paris, are very inaccurate. 2°. Myzooeyle, Blot. 3". 

 Adelges, Vallot. Of this we have two species, A. Laricis, 

 Vallot, and A.gallarum abietis, DeG. ; at least I have found no 

 cause for generic distinction in the structure, notwithstanding 

 the difference of their habitation. IfEriosoma Fagi be assumed 

 as the type of this genus, it Mill be necessary to separate those 

 species which inhabit closed follicles on the leaves and shoots 

 of plants. In that case T would propose the generic name 

 Byrsocrypta for these last. 



XXIII. — On the Formation of the Fibre-formed Cells {Fibrous 

 Cells) or Tubes of the lAber in Plants. By Dr. J. Meyen*. 



While engaged last winter with Prof. Mitscherlich in making 

 a series of observations on the chemical composition of various 

 vegetable substances, the following curious fact attracted our 

 notice : that the purified fibres of flax, and also old linen, 

 when boiled in muriatic acid, decomposed more or less sud- 

 denly into very minute shining particles, which soon settled 

 at the bottom of the fluid. On examining them with the mi- 

 croscope, these particles appeared to be nearly of the same 

 length, and to be formed by a regular decomposition of the flax 

 fibres, so that each particle consisted of a small portion of the 

 cylindrical or prismatical tubes of the flax fibre. Some portions 

 were at times considerably longer ; but then it was more or less 

 evident that these also were composed of several small ones, 

 which were similar in length to the former. At times, how- 

 ever, even the various layers of the thick membrane of which 

 flax fibre is composed were separated from each other by the 

 action of the boiling muriatic acid. 



The examination of a thin unsized linen paper, which had 

 been reduced, by continual boiling in water, to a pulpy mass, 

 exhibited in like manner a manifold division of the single flax 

 fibres into smaller particles, and of their walls into distinct 

 layers : but this subdivision, on which the fabrication of paper 

 evidently depends, was far from being comparable with the 

 • Translated from Wiegmann's Archiv, Part IV., 1838. 



