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VII. Remarks on the Examination of some Fossil Woods, which tend to eluci- 

 date the Structure of certain Tissues in the recent Plant. By Edwin John 

 QUEKETT, Esq., F.L.S. 8fC. 



Read March 18, 1845. 



Among the many disputed points in vegetable anatomy, few have excited 

 more controversy than the structure of spiral vessels, and the markings on the 

 woody fibres of plants belonging to the order Coniferce. Having found in- 

 stances of these structures in the fossil state which appear satisfactorily to ex- 

 plain their nature, the following observations are oflfered to the notice of the 

 Society. In doing so, it is not intended to enter into any detailed account of 

 the minute anatomy of these parts, as it is generally known and already de- 

 scribed in most botanical works. 



From the period of the discovery of spiral vessels in plants by Henshaw, in 

 1661, up to the last quarter of a century, numerous have been the theories 

 respecting their structure ; the older vegetable anatomists, from the imper- 

 fection of their microscopes, were led to form various opinions on these mi- 

 nute organs, which have been recorded in works on vegetable anatomy. The 

 true structure, by the aid of delicate manipulation and improved means of 

 observation, had however, to most recent observers, appeared to be deter- 

 mined ; as it can be shown that these organs are composed of a cylinder of 

 membrane closed at each end, in the interior of which are one or more fibres 

 coiled spirally. This is a fact often to be seen in favourable dissections, and 

 is decidedly manifest when the development of the fibre is watched in the 

 manner I have described in vol. i. of the ' Transactions of the Microscopical 

 Society;' but another opinion has been entertained, that the fibres are coiled 

 spirally on the exterior of the cylinder of membrane, instead of in its in- 

 terior. 



On examining lately a specimen of fossil wood, exhibiting the structure of 



