PREFACE. 



Much of the matter contained in the following pages 

 formed the subject of a lecture, delivered on various 

 occasions to country audiences, in which the attempt 

 was made to popularise an interesting branch of science : 

 Plant structure, life, and growth. For this purpose it 

 mattered little what plants should be selected as illus- 

 trations, but it appeared to me, on reflection, that those 

 which form the basis of our " Strong Drink and Tobacco 

 Smoke " (the title chosen for the lecture) would prove 

 more interesting and instructive than so-called less useful 

 plants. 



The introduction of the tobacco leaf as a subject for 

 analysis was thought desirable, in these days of universal 

 smoke, as affording an illustration of the simple means 

 necessary to detect its spurious substitutes ; thus enabling 

 the smoker to become, if he choose, his own analyst. 

 It affords an opportunity to display some striking 

 illustrations of the variations which Nature elaborates 

 in the minutiae of the leaves of plants. 



