X CONTENTS. 



Page 



magnifying of trifling distinctions due to want of education and of 

 philosophical views . 13 



Physiology, eyil of studying -vvithout prehmiaaiy acquaintance with 

 System, etc. — Defective state of modem botanical instruction, and 

 its eiTects — The value of the study of System evidenced in Whewell's 

 ' History of the Inductive Sciences' — The greatest discoveries in 

 physiological botany developed through the labours of great Sys- 

 tematists, Linnseus, Brown, and Brongniart . 14 



Relative importance of elementary acquaintance with physiology in 

 Animal and Vegetable Kingdoms — Obstacles at outset to students 

 acquiring an elementary knowledge of botany and of botanical ter- 

 minology — Hence necessity of artificial systems for beginners 15 



Vulgar errors more habitual in all that regards the organs of plants 

 than of animals — Requirements for study of Systematic Botany, 

 especially development .... 16 



Necessity of comprehensive knowledge of forms and development im- 

 plies variation — Amount of variation can only be appreciated by 

 consideration of these — Physiology, as a branch of botany, evil of 

 misunderstanding its relation to other branches of the science . IV 



Practical advantages of the study of classiflcation^Defective prelimi- 

 nary education of men intended for scientifie professions 18 



III. Subjects op Variation, Oeioin op Seboies, Speoipio Centees, 



Hybeidizatiou, and Geogkaphioal Disteibution . 19 



DesirabOity of explaining the principles adopted by naturahsts — Vague 

 and unphilosopliieal use of the word Species . 19 



Differences of opinion upon the subject — Lamarck — * Vestiges of the 

 Natural History of the Creation' — Sh- C. LyeE's writings — Our own 

 views — Prevalence of doetrine of niutabihty due in part to faulty 

 education . . . . 20 



Hypothesis of non-existence of species does not diminish the value of 

 the study of Systematic Botany — Necessity in that case of explain- 

 ing the laws that govern the relative mutability and permanence of 

 forms . . 21 



A. Effect's of Hyhridization. 



Difficulties attending the operation . . . . 21 



Its partial effects— Oifspring have no characters foreign to parents, and 

 are almost always barren— Analogy from animal kingdom — Garden 

 hybrids ; arguments from possibility of existence of hybrids in na- 

 ture ; necessity of arguing from such facts on broad principles, and 

 the argument as strong for hybridization obhterating as for making 

 species . .... 22 



Hybrid Thistles, Gentians, and defective information regarding them 

 — Arguments from the experience of Indian botanists 23 



The subject wants systematic study . . . 24. 



