4 FORM AND ABKANGEMENT OF CELLS. 



(^»;giw, to revolve), ellipsoidal cells (fig. 6). 4. Ovenchyma (oiov, an 

 egg), oval cells. Eound, elliptical, and oval cells, are common in 

 herbaceous plants. 5. Gonenchyma (xSvos, a cone), conical cells, as 

 hairs. 6. Columnar cellular tissue, divided into Cylindrenchyma 

 (xvXivS^og, a cylinder), cylindrical cells (fig. 17 a), as in Ohara, and 

 Prismenchyma (-ir^ie/jija,, a prism), prismatical cells, seen in the bark of 

 some plants (fig. 10). When flattened, prismatical- cells form .the 

 muriform (murus, a wall, like bricks of a building) tissue of the 

 medullary rays of woody stems, and when much shortened they 

 assume a tabular form, constituting Pinakenehyma (mva^, a table), 

 tabular cells (fig. 11), or square cells (fig. 9). 7. Prosenchyma (•ffgos, 

 indicating addition), or Atraetenchyma (argaxros, a spindle), fusi- 

 form or spindle-shaped cells, seen in woody structures (fig. 2). 8. 

 Golpenchyma (xoX-rog, a sinus or fold), sinuous or waved cells, as in 

 the cuticle of leaves. 9. Cladmchyma (xXdSog, a branch), branched cells, 

 as in some hairs. 10. Actinenchyma (^axTig, a ray), stellate or radiat- 

 ing cells, as in Juncus and Musa (fig. 16). 11. DcBdalenchyma [baibcCkog, 

 entangled), entangled cells, as in some Fungi. 



Fig. 14. Fig. 16. Fig. 16. 



The size of cells varies not less than their figure in difierent plants, 

 and in dififerent parts of the same plant. They are frequently seen 

 from shs, rhi, to -nnnr of an inch in diameter. In cork, which is 

 cellular, there are about a thousand in the length of an inch. In' 

 the pith of Elder cells tw of an inch in diameter are seen. In 

 many succulent vegetables, and in the pith of some aquatic plants, 

 large cells ranging from t* to A of an inch in diameter occur ; 

 while the cells in spores of Fungi have been computed at Tt^ST of an 

 inch in diameter. In a cubic inch of the leaf of a carnation, there 

 are said to be upwards of three millions of cells. 



Each cell has originally a separate membranous wall, but in the 

 progress of growth the walls of contiguous cells may become united. 

 When cells are united by their extremities (fig. 17), their , partitions 

 are occasionally absorbed so as to form continuous tubes. .W,hen 

 cells are united in a rectilinear manner, those in contiguous rows are 



Figs. 14, 15. Hexagonal cells, cut longitudinally and transversely. Fig. 16. Branching, 

 stellate, or radiating ceUs of Vicia Faba, the common bean. 1 1, Intercellular lacunffi, or 

 air-spaces between tlie cells. 



