STRUCTURE AND ARRANGEMENT OF FLOWERS. 17 



freshly imported seed. In other words, the seed saved under hag pro- 

 duced uniform strains adapted to soil and climatic conditions in this 

 section, while seed saved in the open and subject to cross-fei-tilization 

 with freaks and other undesirable types produced about the same pro- 

 portion of freak plants as the crops grown from the freshly imported 



seed. 



The writers during the past season planted in Florida Connecticut- 

 grown seed of the Sumatra variety. It was found that while there 

 was a noticeable change in the shape of leaf and in some minor char- 

 acters in the Florida-grown tobacco, there was no violent breaking 

 up of type or indication of unusual variability. This experiment 

 and other observations have led the writers to believe that the effect 

 of chaniriuff seed from the north to the south is not accompanied by 

 such marked changes as when seed is taken from tropical conditions 

 to northern latitudes. 



In summing up the observations on this subject it can safely be 

 said that it is a dangerous policy to plant large crops of tobacco 

 with imported seed or with seed from a very different section. In 

 most cases it has resulted in failure and caused considerable loss to 

 the growers. The general crops should be planted from seed pro- 

 duced under the same conditions as the crop which is to be grown. If 

 it is necessary to change the seed or desirable to test imported vari- 

 eties, it should be done on a small scale, followed by a most careful 

 selection of seed plants, and the seed should be saved under bag, safe 

 from cross-fertilization. 



THE STRUCTURE AND ARRANGEMENT OF FLOWERS. 



A careful study of the tobacco flower is one of the most essential 

 factors in the beginning of tobacco breeding. Successful results, 

 particularly in the production of new varieties, can seldom be ob- 

 tained until one becomes familiar with the structure of the parts of 

 the flower and the manner in which these parts perform their sev- 

 eral functions. A full realization of the ease with which crossing 

 takes place can only be obtained in this way, and, as has been pre- 

 viously stated, the prevention of promiscuous cross-pollination is 

 of first importance in the production of a desirable and uniform type 

 of tobacco. 



The tobacco flowers are arranged upon a branching determinate 

 flower head, which appears when the middle leaves are about half 

 grown and continues to develop and produce new flowers during the 

 rest of the life of the plant. Figure 3 is a diagrammatic sketch of 

 a tobacco flower, showing the parts of the flower and the general way 

 in which pollination takes place. The calyx (a) is the outer, green, 

 five-parted, floral envelop at the base of the flower which serves to 

 15507— No. 96—07 m 2 



