STRUCTURE.] FIBROCELUJLAR TISSUE. 53 



is what is found in Oncidium altissimum leaves, in the 

 aerial roots of some Orchids, in the lining of many 

 anthers, and is what Mohl has figured (Ueber die 

 Poren, fyc. tab. 1. fig. 9), from the pith of Rubus odoratus. 

 It approaches very nearly to the nature of spiral vessels, 

 hereafter to be described, and appears only to be distin- 

 guishable by the spires of the fibres not being in contact, 

 being incapable of unrolling, having no elasticity or 

 tenacity ; and by the bladders not being cylindrical and 

 tapering to each end, but spheroidal. It is easily 

 examinable in Pleurothallis ruscifolia, and forms upon 

 the side of the cells elevations which give them a beauti- 

 fully pitted appearance when cut across. In the sub- 

 cutaneous parenchym of the leaves of this plant the 

 fibres of one cell are placed exactly opposite those of the 

 next cell, so that sections of the walls exhibit double 

 depressions and elevations all along the line, so regular 

 that, unless a very good microscope is used, they appear 

 to form open passages from one cell to the other. 



2. Fibres crossing each other spirally, and forming a reti- 



culated appearance by their anastomosing within oblong 

 bladders. Of this nature are the reticulated cells of the 

 seed-coat of Maurandya Bar clay ana, Wightia gigantea, 

 and the like. (Plate I. fig. 11.) In the seed of Soymida 

 febrifuga there lies in the middle of the wing a thick 

 stratum of fibro-cellular bodies, which would be regarded 

 as spiral vessels if they were longer and more cylindrical ; 

 but which seem to belong to this form of fibro-cellular 

 tissue. 



3. On the surface of the seed of the almond Mr. Quekett 



observed numerous projecting cells which have very 

 thick parietes : these can be found burst and their con- 

 tents emitted; in fact they look more like eggs of 

 some minute insect, which however they are not, because 

 if the seeds of unopened almonds are examined, these 

 bodies will be found there likewise : they appear to be 

 analogous to the cells on the seeds of Cobsea scandens, 

 which Don describes as mealiness, but which are instead, 

 most beautiful examples of fibro-cellular tissue. 



