Mr. Lindley on Vegetable Tissue. 265 



such as may arise from the adhesion of grains of grumous 

 matter to them, and evidently consist of nothing but a very 

 delicate membrane. This, which is the general character of 

 cellular tissue, is not unfrequently considered its absolute dis- 

 tinction ; it appears, however, from recent observations, that 

 it is subject to some very remarkable modifications. 



It is an old idea, that the membrane of all tissue is composed 

 of interlaced fibres, but this opinion seems to have originated in 

 theoretical views, and either not to have been founded upon ob- 

 servation at all, or at least, not upon accurate observation ; the 

 existence of such fibres, in any case, has been denied by Mirbel, 

 Link, and others ; and it must be evident to any one, that, in 

 cellular tissue generally, no trace of them is visible. Molden- 

 hauer, however, noticed, so long since as 1779, that the cel- 

 lules of the leaf of Sphagnum obtusifolium are marked by 

 fibres twisted spirally; but this met with scarcely any attention. 

 Link states, that his supposed fibres are nothing but the lines 

 where small cells, contained in a larger one, unite together ; 

 and other botanists pass by the subject without remark. It is, 

 nevertheless, certain, that the observation of Moldenhauer was 

 perfectly correct, and that the cellular tissue of Sphagnum con- 

 sists of a membrane, within which a fibre is twisted in an irre- 

 gularly spiral manner ; it also appears that this kind of struc- 

 ture is far from uncommon. In November, 1827, I described 

 the tissue of the testa of Maurandya Barclaiana (See Botanical 

 Register, t. 1108) as consisting of cellules, formed of spiral 

 threads crossing each other, interlaced from the base to the 

 apex, and connected by a membrane ; this was named, at 

 the time, reticulated cellular tissue, and an approach to it has 

 since been remarked in the seed-coat of several Bignoniacese. 

 In 1828, Dr. Mohl stated, that in the pith of Rubus odoratus, 

 he had seen cellules, the walls of which were marked with delicate 

 fibres having a reticulated appearance ; and that other cases 

 existed, in which the fibres (instead of being reticulated) formed 

 curved lines, parallel with each other (see his Memoir uber die 

 poren des Pflanzen-zellyewebes). In August of the same year, 

 I was so fortunate as to discover upon the testa of Collomia 

 linearis, the existence of incredible numbers of spiral fibres, 

 * lying coiled up spire within spire, and confined by a dry 



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