_ i)8 - SECRETION AND EXCRETION. 



60. Gum. Secretory gland-hairs of a leaf seen under the microscope. 



61. Etherial oil in Citrus plants: 



(a) Oil-glands of lemon leaves seen with the naked eye. 



(b) Leaves crushed and smelt. 



(c) Section of orange epicarp showing oil-glands under the microscope. 



62. Etherial oil in Eucalyptus leaves. 



(a) Leaves smelt before and after crushing. 



(b) Oil-glands seen under the microscope in section. 



