16 FUNCTIONS OF NUTRITION. 



27. SCURF consists of thin flat membranous disks, with a 

 ragged margin, formed of cellular tissue springing from the 

 epidermis. It may be considered as a modification of hairs ; for 

 it differs from those bodies only in being more compound. 



28. Prickles are conical hairs of large size, sharp pointed, and 

 having their tissue very hard. They differ from thorns in being 

 fixed to the bark ; the thorn is fixed to the wood. 



29. Glands. We give the name of glands to those organs 

 which are destined for the secretion of particular liquids : they 

 are found in almost all parts of plants; they are small cavities, 

 sometimes formed of cellular tissue only, and sometimes of very 

 little cells mingled with a great number of vessels ; in other 

 respects, they do not appear to differ essentially from the tubiform 

 reservoirs we have already mentioned under the name of proper 

 vessels. 



CLASSIFICATION OF THE ORGANS AND FUNCTIONS OF VE- 

 GETABLES. 



30. The functions of vegetable are referred to two classes. 

 One belongs to the individual life of the vegetable, that is, the 

 functions which effect its nutrition : the other refers to its multi- 

 plication or the preservation of the species. 



31. The parts of plants that serve the functions of nutrition, 

 are the roots, the stem, and the leaves. 



32. The parts which are especially designed to secure the mul- 

 tiplication of plants are the organs of fructification ; namely, the 

 flowers and fruits. 



LESSON II. 



FUNCTIONS OF NUTRITION. Absorption and Ascent of Sap 

 Roots, their Structure and Forms Stem, its Divisions, 

 Varieties, fyc. Structure of the Stem in Ex'ogens Medul- 

 lary Canal Pith Medullary Sheath Wood Medullary 

 Rays Bark Epidermis Cork Structure of the Stem in 

 En'dogens. 



FUNCTIONS OF NUTRITION. 



1. The phenomena of the life of nutrition in plants are referred 

 to five distinct functions ; namely, 



27. What is scurf? 



28. \Vnat are prickles ? How do they differ from thorns? 



29. What are glands ? 



30. How many kinds of functions do plants possess ? 



31. What parts serve the function of nutrition ? 



32. What parts serve the function of multiplication, or reproduction of 

 plants ? 



1, What are tne several functions of the life of nutrition? 



