624 



tweeu Stokenchurch, Oxfordshire, and Cadmore Eud ; Hystencum rubrum, found ou 

 bean-stalks at Aston-Rowant and Tetsworth, Oxfordshire. Specimens were presented 

 by Dr. Ayres. 2. " On the Groups into which the British Fruticose Rubi are divisi- 

 ble," by Mr. Edwin Lees, F.Ii.S., &c. This paper (which was illustrated by speci- , 

 mens and drawings) will be concluded at the next meeting, when a full report will be 

 given. — G. E. D. 



MICROSCOPICAL SOCIETY OF LONDON. 



May 17. — J. S. Bowerbank, Esq., F.R.S. in the chair. Read, a paper from E. J. 

 Quekett, Esq., " On the Nature of Vessels possessing longitudinal as well as spiral 

 Fibres." Mr. Quekett stated that these vessels are not present in the majority of plants, 

 and consequently have not been described until within the last few years. They have 

 been found in plants belonging to very different orders, by various observers, and it is 

 not improbable that future investigation may detect them in many other plants than 

 those in which they have hitherto been observed. Thus they have been found by 

 Schultz in Urania speciosa, by Mr. W. Wilson in Typha latifolia, in a plant of the 

 gourd kind by Mr. Hassall, and by Mr. Quekett in Loasa and in Canna bicolor. In 

 exogens these vessels do not appear to be either of the length or diameter they are in 

 endogens, in which they seem to constitute the largest and longest of the vessels. In 

 Loasa they do not exceed the ^l of an inch in diameter, while in Urania and Canna 

 they are nearly the ■^. In their structure they have a general resemblance to ordina- 

 ry spiral vessels, having very frequently two or more fibres fonning the same screw 

 coiled in the interior of the vessel, as in compound spiral vessels. In addition to this 

 spiral arrangement, there are longitudinal deposits of fibres whose number varies con- 

 siderably, some vessels not having more than six or eight, while more than double 

 that number may be detected in the larger vessels. Upon applying force, these lon- 

 gitudinal fibres are broken at the same point as the membrane, the broken edges of 

 which project beyond the edge of the spiral ribband to which the vessels are reduced. 

 Their terminations are very pointed, and they are applied to each other for some con- 

 siderable space. At first Mr. Quekett supposed these vessels to be perfect of their kind, 

 presenting higher marks of development than the true spiral vessels ; subsequent ob- 

 servations however have enabled him to discover that a vessel presenting this longitu- 

 dinal deposit of fibres, is only in a state preparatory to the complete development of a 

 vessel exhibiting oval or quadrangular dots on its parietes : and he observes that al- 

 though a tendency to produce longitudinal fibres may be seen in other annular and 

 spiral vessels, it is only in the compound spiral that the ultimate conversion of a spi- 

 ral vessel into one with dots regularly arranged in longitudinal fibres occurs. This is 

 quite in accordance with the observations of Mohl and Schleiden, which prove that the 

 spiral is the earliest type of every other form of vessel, whatever phases they may after- 

 wards assume. He also described the various steps by which the spiral vessel becomes 

 an annular one, and the reticulated vessel one with dots; and showed that the vessels 

 forming the particular subject of this paper, are some of those in progress towards the 

 dotted condition, as in some instances, in Canna bicolor, the various steps of this pro- 

 cess can be witnessed in different parts of the same vessel. He concluded with some 

 observations upon the dots on the vessels in woody exogens, showing that these last are 

 of a more complex structure than those formed by the mere rounding of the meshes of 

 the reticulated vessel. — J. W. 



