CHAP. I. CELLULAR TISSUE. 18 



constitutes the lining of the valves of almost all anthers. Tlie 

 forms under which it exists in these parts are far more various 

 than those of membranous cellular tissue. The principal 

 varieties are these : — 



A. Membrane and Fibre combined. 



1. Fibres twisted spirally, adhering to a spheroidal or angu- 

 lar membrane, and often anastomosing irregularly, without the 

 spires touching each other. (Plate I. fig. 12.) This is what 

 is found in Oncidium altissimum leaves, in the aerial roots of 

 some Orchideous plants, in the lining of many anthers, and is 

 what Mohl has figured ( Ueber die Poren, Sj-c. tab. i. fig. 9.), 

 from the pith of Rubiis odoratus. It approaches very nearly 

 to the nature of spiral vessels, hereafter to be described, and 

 appears only to be distinguishable 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 cylindri- 

 cal and tapering to each end, but spheroidal. 



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

 culated appearance by their anastomosing within oblong blad- 

 ders. Of this nature are the reticulated cells of the seed-coat 

 of Maura ndya Barclayana, Wightia gigantea, and the like. 

 (Plate I. fig. 11.) 



3. Fibres running spirally close together, except at certain 

 -places where they separate and leave between them small 

 spaces, which appear like dots. 



4. Fibres running spirally, but completely grown together 

 except at certain spaces where they separate and leave small 

 dot-like spaces. This and the last have been noticed by Mr. 

 Valentine in Orchideous plants, and have been extremely 

 well figured by Slack. {Trans. Soc. Arts, vol. xiix. t. 6. 



/ 5, 6.) 



5. Fibres running straight along the sides of truncated 

 cylindrical cells in the anthers of Calla aethiopica and many 

 other plants. (Plate I. fig. 13.) 



6. Fibres running transversely in parallel lines round three 

 of the sides of prismatical right-angled cells, in the anthers 

 of Nymphaeaceae, &c. 



