Unisexual Crosses 273 



cies, and to the almost incredible number of 

 combinations which are possible between their 

 characters. The first of these crosses was 

 made in the nursery of Veitch and Sons near 

 London by Seden, and the first hybrid is ac- 

 cordingly known as Begonia Sedeni and is still 

 to be met with. It has been superseded by sub- 

 sequent crosses between the Sedeni itself and 

 the Veitchi and rosiflora, the Davisii, the 

 Clarkii and others. Each of them contributed 

 its advantageous qualities, such as round flow- 

 ers, rosy color, erect flower stalks, elevation of 

 the flowers above the foliage and others. New 

 crosses are being made continuously, partly be- 

 tween the already existing hybrids and partly 

 with newly introduced wild species. Only 

 rarely is it possible to get pure seeds, and I 

 have not yet been able to ascertain whether the 

 hybrids would come true from seed. Specific 

 and varietal characters may occur together in 

 many of the several forms, but nothing is as 

 yet accurately known as to their behavior in 

 pure fertilizations. Constancy and segregation 

 are thrown together in such a manner that ex- 

 treme variability results, and numerous beauti- 

 ful types may be had, and others may be ex- 

 pected from further crosses. For a scientific 

 analysis, however, the large range of recorded 

 facts and the written histor\% which at first sight 



