348 JSex Characters in Begonias 



especially in birds. (See H. Poll, "Zur Lehre von den sekundaren 

 Characteien " (Stzgtibei: Ges. Naturf. Freunde zu Berlin, 1909) ; 

 C. J. Bond, "On a case of Unilateral Development of Secondaiy Sex 

 Characters in a Pheasant" {Journal of Genetics, Feb. 1914).) In this 

 connection also the limitation of paternal and maternal characters to 

 opposite sides of the body in the larvae of some sea urchin hybrids 

 reared by Herbst as the result of artificial fertilization is of great 

 interest. (See J. Loeb, Artificial Favthenogenesis.) Although I am 

 not aware of any recorded observations of the limitation of paternal and 

 maternal characters to apposite halves of the individual in the cotyle- 

 donary .stage in seedling plants, yet such limitation does undoubtedly 

 occur at a later stage of growth, for both individual leaves and opposite 

 branches may sometimes show a hemilateral arrangement of paternal 

 and maternal characters. 



Certain conditions in animals suggest that in addition to the 

 bilateral type of architecture, the individual organism is also built up 

 on a serial or segmental plan, thus sex abnormalities like hermaphro- 

 ditism may show a segmental distribution in birds. (C. J. Bond, 

 Journal of Genetics, Feb. 1914.) In plants also the distribution of the 

 unisexual florets in the compound inflorescence follows in some abnormal 

 cases a distinctly segmental or periodic type. This is well seen in the 

 irregular inflorescence of some abnormal maize plants. Plate XVII, 

 fig. 1, shows a serial alternation on the same peduncle of male and 

 female florets. Plate XVII, fig. 2, shows a magnified view of the same 



th 



ng. 



PART II. 



Secondary Sex Characters in Begonias. 



It has already been pointed out that the normal male flower of the 

 monoecious Begonia has four petals and the normal female flower five. 

 Although this association between the sex of the flower and the number 

 of petals seems characteristic of most Begonias under normal conditions, 

 yet it is not an absolutely constant feature. For instance a flower may 

 develop an outer whorl of pistillate structures on its staminate floral 

 axis. It may even show exposed ovules on some of these pistillate 

 leaves, it majf in fact be partly a female flower and yet retain the four 

 petals characteristic of the male flower. (See PI. XVI, figs. 8, 4, 8.) In 

 the same way the jjrimarily female flowei' may have a row of .stamens 



