CONTENTS. XI 



Page 



B. On Variation of Species. 

 . Ignorance of laws governing variation — Indications of laws deduced 

 from considerations of climatic conditions and distribution — Gene- 

 ral rules deducible from them •....•• 24 



Arguments from the permanence of forms of foreign plants in the 

 Calcutta Botanic Gardens — Specific effects of climate in altering 

 familiar plants difficult of appreciation, because of impossibility of 

 recollecting habit, and interference of local associations . . 25 



Relations between climate and development of species in India as in- 

 stanced by the Floras of equable and extreme climates . . .26 



Comparison with the Floras of the Cape of Good Hope, Australia., 



etc. ; 'prima facie evidence afforded in favour of definite creations 



of species 



27 



Variation of species a fruit fid study — 1. Variation in organs of indi- 

 viduals easily studied in India — Changes during growth in differ- 

 ent parts of the individual, hi distribution of the sexes . . .27 

 Exaggerated estimates of species of known plants due hi part to narrow 

 ideas of power of variation — Relative size and symmetry not im- 

 portant in the Vegetable Kingdom, as compared with the Animal . 28 

 Variations in floral organs : ovary, carpels, sepals . . . .29 



2. Variation between different individuals of the same species . . 29 

 This a fertile source of bad species — Variation in colour of flowers, 

 odour, hairiness, medicinal and economic properties — Variations 

 from change of locality — Necessity of studying variations amongst 

 gregarious plants — Instances in the Cedar, Deodar, and other Co- 

 niferce, Picea Webbiana and Abies Smithiaua . # . .30 



Arguments from different wood of the same native tree in Britain, 

 Europe, etc. . . . 32 



Development of medicinal and other properties, as in Tea, Opium, 



etc., in India 



32 



Habit — Erroneous importance attached to . . - .32 



Illustrated by Pines and other European and Indian trees, shrubs, 



and herbs 33, 34 



Arguments derived from European cultivated trees — False impres- 

 sions of habits of common trees, instanced by the Deodar in Eng- 

 land — Desirability of pursuing the study of species on a different 

 principle ........... 35 



C. Geographical Distribution. 



Difficulties in the way of its study, with reference to India especially 

 Our ignorance of the prominent features of Indian vegetation — Want 

 of any work on the subject 36 



Necessity of studying the replacement, ap] iranee, and disappearance 

 of types — Anomalies in distribution of Indian plants — Absence of 

 Oaks and Pines hi the Peninsula, and of Cyeadsm hi Ceylon . . 37 



Great increase to supposed number of species arising from m i sta k en 



