Dr. M. J. Schleiden on Spiral Formations. 



35 



IV. — Observations on Spiral Formations in the Cells of Plants, 

 By Dr. M. J. Schleiden, Professor of Botany in the Uni- 

 versity of Jena*. 



[With a Plate.] 



The first discoverer of spiral vessels, it matters not whether 

 Henshaw, Malpighi, or Grew, was without doubt astonish- 

 ed in the highest degree by their elegant tissue; and the 

 more he became acquainted with them, the more varied the 

 forms unfolded before the eyes of the ingenious observer, the 

 more eagerly attention must have been directed to this appa- 

 rently so remarkable formation. Thence it happened that, 

 although not agreed respecting the kind and manner, a 

 higher import with regard to vegetable life was generally 

 assigned to these parts in opposition to the cellular tissue. 



It was soon, however, found necessary to place the annular 

 and porous vessels by the side of the spiral vessels ; and not 

 relying on the observation of actual facts, but chiefly induced 

 by their representative occurrence in similar or analogous 

 parts, and misled by a false explanation of that actually ob- 

 served, Link assumed the metamorphosis of these forma- 

 tions into one another, without, however, at the time ex- 

 pressing decidedly whether an ideal or real metamorphosis 

 was intended. How far, then, this was from a correct compre- 

 hension of the matter, is shown by his subsequent writings 

 and annexed illustrations, in which he still explained the 

 fibres as the thinner places, and the elongated pores as re- 

 mains of the thicker fibres, a view which he still entertained 

 in 1831, with the greatest confidence, for the porous vessels. 

 A view differing much from Link's, but quite as erroneous, was 

 supported by Kieser ; and even Meyen, in his c Phytotomie,' 

 declared the pores to be the remains of torn spiral fibre. 



What, on the other hand, is at present understood by the 

 word metamorphosis of the spiral vessels, has nothing in 

 common with the earlier views, except the name retained for 

 convenience sake; and by this alone Meyen seems to be 

 misled, when in his Physiology (p. 139) he ascribes to Link 

 the merit of having first decidedly advanced this doctrine. 

 This is the more evident, as Link himself, in his latest edi- 

 tion of the e Philosophia Botanica/ is still far from compre- 

 hending all the facts belonging to this subject, and compri- 

 sing them under a correct point of view. 



If we at present express the fundamental conception of 

 this doctrine thus : " The thickening layers deposited on the 



* Translated from the Flora, No. 21 and 22. June, 1839. 

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