62 STUDIES IN INDIAN TOBACCOS. 



or tropical conditions, to the north, are considered by Shame 1 

 and Cobey' to be some of the causes of variation in the tobacco 

 plant. Killebrew and Myrick"^ consider that soil and climate 

 are two causes constantly in operation in increasing the number 

 or in modifying the character of existing varieties, Lock'^ 

 states : " As the Havanna tobaccos command the highest prices, 

 the cultivator nearly everywhere attempts to introduce and 

 cultivate them. There is no great difficulty in raising plants of 

 these varieties, but they speedily degenerate and form new 

 varieties, if the climatic conditions, etc., are not favourable. 



The 2;rowth of the collection of Indian tobaccos at Piisa 

 in 1905 afforded us an admirable opportunity of studying the 

 effect of a new locality on the various forms and also the effect of 

 soil and manuring. If the types of tobacco easily change, some 

 alteration should be manifest after four years in the case of forms 

 collected from such widely different localities as Burma, Assam, 

 Madras and the Punjab. If, as is sometimes thought, introduced 

 tobaccos gradually assume tlie form of those ordinarily cultivated in 

 the district, the process should by this time have manifested itself at 

 Pusa. Observations on the various types and photographs of actual 

 plants for several years have, on the other hand, clearly demon- 

 strated the remarkable uniformity of the types from year to year 

 even to fine shades of colour and small differences in the morphol- 

 ogy of the leaves and flowers and in the earliness and general 

 habit of the plant when raised from self- fertilized seed. The same 

 applies to the various types of Nicotiana rustica which w^e have 

 examined, when grown from self-fertilized seed. No tendenc}^ 

 to break up has been noticed, the types breed true in the most 

 remarkable manner and there is no evidence of any transition 

 on the part of the introduced forms tow^ards the coarse-leaved 

 sorts cultivated in Bihar. Excessive amounts of nitrogenous 

 manure and over-watering have a marked effect on the vigour and 



1 Sharael & Cobey, BvU. 96, Bureau of Plant Industry, U. S. Department of Agricnitvre 

 1907, p n. 



2 Killebrew & Myiick, Tohacvo Leaf, N-ew York, 1900, p. 30. 



*" I,ock, Toharco groivifig, curing and manvfaeturhig, London 1903, p. 32, 



