28] 



CHAPTER II. THE TISSUES. 



97 



the other, is in solution, and is excreted at the surface. In the 

 chalk-gland the secretum escapes through a special channel, a 

 ivater-stomq_ (p. 108). In the nectary the secretum is simply 

 poured out on the surface of the gland. 



(6) Hollow multicellular glands are intercellular spaces sur- 

 rounded by secreting cells, and are, in some cases, of schizogenous, 

 in others of lysigenous, origin (see p. 89). The secretum may be 

 mucilage, or gum, or a mixture of gum and resin (gum- resin), or 



Fia. 76. Lysigeuous oil-gland below 

 the upper surface of the leaf of Dicta in- 

 nut Fraxinella ( x 320) : B at an early 

 stage ; C mature ; c mother-cells of the 

 gland before their absorption ; o a large 

 drop of ethereal oil. (After Sachs.) 



Fia. 77. Schizogenoua resin-duct in the 

 young stem of the Ivy (Hedera Helix), transverse 

 section ( x 800) : A an early, E a later, stage ; 

 g the resin-ducts ; c the cambium ; icb the soft 

 bast; b bast-fibres: rp cortical parenchyma. 

 (After Sachs.) 



ethereal oil, or a mixture of ethereal oil and resin (balsam). The 

 cavities are either rounded closed spaces, or are elongated canals, 

 extending for some distance through the tissue ; the former are 

 usually of lysigenous, the latter of schizogenous, origin. 



As examples of lysiyenous hollow glands, may be mentioned the 

 cavities filled with gum, which occur in the tissue of Cherry-trees ; 

 the oil-glands of the Orange and Lemon, and in the leaves of the 



