448 Dr. Willshire on some points of Vegetable Structure. 



obovatis ochraceis, capillitio supra libero obovato erecto spo- 

 ridiisque concoloribus. Darw. No. 224. 



On the rough bark of palms. Rio Janeiro. May 1832. 



Growing in little gregarious patches about a line high. Stem 

 about as long as the peridium, which is smooth, shining, of a yellow 

 ochre, breaking away gradually above, but persistent at the base, and 

 crateriform. Capillitium free above, slightly attached below, some- 

 times falling out entire from the peridium. Sporidia globose. 



This plant has very much the habit of Trichia davata, of which 

 species I considered it a form till I examined the capillitium, which 

 is that of an Arcyria, being reticulate, and not filled with spiral 

 threads. 



Plate X. fig. .J. a, plants of Arcijrla decipiens magnified ; h, capillitium, 

 ditto ; c, portion of capillitium with sporidia highly magnified. 



XLVIII. — Remarks on some points of Vegetable Structure. 

 By W. Hughes Willshire, M.D., M.B.S., Lecturer on 

 Botany at Charing Cross Hospital, &c. 



[With a Plate.] 



In the last number of the ' Linnrea' appears a paper of Mohl's*, 

 in which the origin of a secondary layer out of spiral fibres in 

 a vessel is denied, as also that the punctations in dotted tubes 

 depend for their presence upon the existence of this secondary 

 internal layer. Yet in another paragraph of the same paper 

 it is also stated, that the first approach towards the develop- 

 ment of the punctations is seen in the existence of a delicate 

 fibrous net upon the lateral walls of the vessels, especially of 

 those which lie next to other vessels. Now from this latter 

 statement it certainly appears, that the presence of fibres is 

 admitted by Mohl though denied in another, and also from 

 his averment that this fibrous net is seen upon the lateral 

 walls — w hich we take to mean externally to the homogeneous 

 membrane of which the vessel is at first composed ; we as- 

 sume that he here admits its formation to be secondary in re- 

 gard to period of development, though its situation is outward. 

 Though it is denied by Mohl that the fibres are spiral, from 

 what we have just stated, however, we could draw no other con- 

 clusion than that the existence of a secondarily formed fibrous 

 layer is admitted, did it not appear contradicted afterwards 

 by his stating that no network or fibres exist per se, but are 

 only appearances. The author says, " the meshes of the net 

 answer to the after-present circles of the dot, consequently 



* A translation of this valuable paper by the Rev. M. J. Berkeley ap- 

 peared, together with the plates, in our last number, — Edit. 



