Production of Double Flowers 511 



send me such a curious flower. One half of it 

 was completely double, while the other half was 

 entirely single, bearing normal and fertile sta- 

 mens in the ordinary number. 



The same halfway doubling is recorded to 

 occur among composites sometimes, and from 

 the same source I possess in my collection a 

 head of Pyrethrum roseum, bearing on half of 

 its disk elongated corolla tubes, and on the 

 other half the small disk-florets of the typical 

 species. 



It is a current belief, that varieties are im- 

 proved by continued culture. I have never been 

 able to ascertain the grounds on which this con- 

 viction rests. It may be referred either to the 

 purity of the race or to the complete develop- 

 ment of the varietal character. In the first case 

 it is a question of hybrid mixtures from which 

 many young varieties must be freed before be- 

 ing placed on the market. But as we have al- 

 ready seen in a former lecture, this requires 

 only three or four years, and afterwards the 

 degree of purity is kept up to the point which 

 proves to be the most suitable for practical 

 purposes. The complete development of the 

 varietal character is a question restricted to 

 ever-sporting varieties, since in white flowers 

 and other constant varieties this degree is va- 

 riable in a very small and unimportant meas- 



