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XX. — Remarks on a peculiar form of Spiral Vessel. 

 By Arthur Hill Hassall, Esq. 



Read Nov. 16, 1842. 



While recently engaged in examining the decayed gourd of the 

 vegetable marrow, with the view of finding the Fungi which are so 

 influential in producing the destruction of fruits, my attention was 

 directed to a peculiar modification of spiral vessel. On placing a 

 bundle of the spiral vessels of the gourd of this plant beneath the 

 microscope, each vessel is plainly seen to be striated by a number of 

 longitudinal lines, which might, at first sight, be regarded as plaits in 

 the enclosing membrane of the spiral fibres, but are really secondary 

 Jibrilla; as may be proved, — first, by the circumstance that they are 

 distinctly separable from this membrane, and secondly, by the fact, 

 that if a spiral vessel be broken up, and the fibre uncoiled, the 

 longitudinal strice will be observed to have separated into numerous 

 short pieces, which adhere to each turn of the spiral fibre; and again, 

 that if an interior view of a vessel be obtained, the extremities of the 

 stria may be plainly seen interrupting its circularity. These longi- 

 tudinal jibrill<B are very numerous, varying in number from six or 

 eight in the smaller vessels, to as many as twenty in the larger (see 

 PI. xix. fig. 1, 2, 3). They are very much smaller than the spiral 

 fibres, to the internal surface of which they are attached ; and the 

 only office which can apparently be assigned to them, is that of 

 strengthening the walls of the tubes, and preventing, by their adher- 

 ence, the too great protrusion of the investing membrane of the vessel. 



On describing this form of vessel, which I had imagined to have 

 been unobserved, to Mr. E. J. Quekett, that gentleman informed me 

 that he had himself noticed it, and supplied me with the following 

 information respecting it : " The first figure of a vessel with longitu- 

 dinal strice which I have seen, was in * Schultz's Memoir on the Cir- 

 culation of the Ducts of the Latex, 1 from Urania speciosa, though I 

 had previously seen it in Loasa contorta, in the petiole. It has been 

 observed since by Mr. W. Wilson, in Typha latifolia, and I have 

 recently found it in Canna hicolor" 



