100 



PART II. ANATOMY AND HISTOLOGY. 



[28 



More commonly, as in the Cichoriese (e.g. Dandelion, Scorzonera), 

 the Campanulacese, and in most Papaveracese (e.g. Poppy), the 

 cell-fusions take place in all directions, producing a dense network 

 (Fig. 80). 



Structures apparently of the nature of laticiferous vessels occur 

 in certain Basidiomycetous Fungi (e.g. Lactarius). 



(e) Laticiferous ccenocytes, commonly known as ''laticiferous 

 cells," occur in some Euphorbiacese (the Spurges), in the Urti- 

 cacese (Nettles), Apocynaceae, and Asclepiadacese. As already ex- 

 plained (p. 64), these " cells " are really 

 coenocytes ; they are visible in the early 

 stages of the development of the embryo, 

 and they grow and branch in the tissue 

 as if they were independent organisms 

 (Fig. 81). As they extend from one end 

 of the plant to the other, they attain a 

 very considerable length in many cases. 

 Their walls are frequently thickened 

 (e.g. Euphorbia), but, like those of the 

 laticiferous vessels, they are not lignified. 

 They contain protoplasm with many 

 nuclei which multiply by division, and 

 in the older parts latex is abundantly 

 present. The latex of the Euphorbiacese 

 contains curious rod-like or dumb-bell- 

 shaped starch-grains. 



(/) Epidermal Glands. Whilst all 

 the preceding forms of glandular tissue 

 are developed in the internal tissues of 

 plants, somewhat similar glandular 

 structures are developed from the super- 

 ficial layer (epidermis), most commonly 

 in the form of hairs (p. 46), either 

 unicellular or multicellular. When the 

 multicellular hair consists of a single row of cells, the secretion is 

 generally confined either to a large terminal cell, or to several of 

 the distal cells ; in any case the secretion begins with the terminal 

 cell, and extends backwards to other cells towards the base. The 

 gland, though epidermal in origin, does not, however, always pro- 

 ject from the surface, but may be more or less sunk in the internal 

 tissue (e.g. glands in the leaf of the Psoralea hirta}. 



FIG. 81. A portion of a lati- 

 ciferous coenocyte dissected out 

 of the leaf of a Euphorbia. ( x 

 120: after Haberlandt.) 



