PREFACE. 



Vll 



important, vegetable products have been mentioned and 

 briefly described. The order of sequence of the groups is 

 that used by "Weisner in his Bohstoffe des PflnnzenrekheSj 

 a book which is the source of much of the information, 

 especially of that relating to anatomy, contained in this 

 part. 



The Appendix contains suggestions that will, it is hoped, 

 be of advantage, especially to those who study without the 

 assistance of a teacher. 



All minute measurements have been given in fractions 

 of an inch, although the great advantage of the use of 

 the metric system is not in the least questioned. But 

 pupils are not, as a rule, familiar with the latter, and can 

 only slowly and gradually be taught to substitute it for 

 what they have learned in early youth and practiced since. 

 The same in substance may be said with reference to the 

 Centigrade and Fahrenheit's thermometers, the familiar 

 scale of the latter being used in this work. Especial 

 attention is called to the tables given in the Appendix of 

 the equivalents of an inch in millimetres, also the equiva- 

 lents of the degrees of Fahrenheit's scale in degrees on tho 

 Centigrade scale. 



Nearly three hundred of the illustrations are original. 

 Figs. 223a and 324a were taken, by permission of the 

 publishers, from Wood's Glass-booh of Botany; Figs. 134, 

 135, and 308 from Gray's Botany; Figs. 342, 343, 344, 

 345, 346, and 347 from Le Conte's Geohgy; Figs. 148.^ 



