40 TOBACCO BREEDING. 



problem, nor does the improvement in methods of culture exhaust 

 the possibilities in the production of uniformly good-burning tobacco. 

 There are no cases on record of previous efforts having been made 

 to improve by breeding and seed selection the combustibility of the 

 varieties of tobacco. Believing it possible to produce better burn- 

 ing varieties in this way, the writers have endeavored in the course 

 of their experiments during the past three years to produce strains 

 of cigar-wrapper varieties which will burn more freely and uni- 

 formly than those which are grown at present. 



Sufficient progress has been made to show very clearly that the 

 variability in burn of tobacco produced by different plants is not 

 altogether due to favorable or unfavorable conditions of soil, vari- 

 ations in kind or quantity of fertilizers, or to methods of fermen- 

 tation, but that the individual plants themselves possess some innate 

 character which bears a marked relation to the nature of the burn 

 of the leaves. It is not definitely known whether this is due to the 

 capacity of different plants to take up and assimilate the chemical 

 constituents of plant food in different proportions or whether it is 

 due to the difference in the physiological constitution of the leaves. 

 To the practical tobacco grower it is of little interest to know the 

 exact reason for this variability^, but it is of most vital interest to 

 him to know that it does occur, and that the good or poor burning 

 quality of the plant is uniformly transmitted to its progeny, so that 

 the nature of the burn can be largely controlled by seed selection. 

 A difference in the soil or fertilizer, or in the treatment of the crop, 

 always has a greater or less influence on the burn of tobacco, and 

 must be taken into consideration ; but in ordinary crops of tobacco, 

 where all conditions are as nearly equal as possible, this marked vari- 

 ation in the burning quality of the individual plants still occurs. 



The writers have found plants belonging to the same variety 

 groAving side by side under uniform field conditions which showed 

 the widest variation in the nature of the burn. The product of one 

 type of plant would burn freely and evenly, while that of another 

 type had a very poor combustibility. This variation in burn can 

 not be explained on the ground of any difference in soil or cultural 

 treatment, but can only be understood by assuming that there are 

 innate differences in the individual plants in this respect. The 

 Avriters have proved beyond a doubt that this innate character does 

 exist and is hereditary. Experimental plots of tobacco grown from 

 the seed of the good and poor burning plants have shown that this 

 character is extremely uniform in the progeny, provided other con- 

 ditions are equal. Plate VII shows two roAvs of tobacco groAving 

 side by side, one of which produced a tobacco that burned very sat- 

 isfactorily, while the product of the other Avas A r ery deficient in com- 



96 



