STUDIES OX THE GENETICS OF FLOWEU-COLOVRS, ETC. 103 



Cross IV. Whüc-Ix tchitc- II and vice versa, etc. (PI IT, fig. 8 nucl 7). 

 ccrrhh x ccRIiJiJi F, = cclirBh. 



At the begiuumg of my breeding exp3rirQents I Imve couductecl the crosses 

 between tlie various white varieties, bociuse it was thought rut to be impossible 

 that the cross of two ceiiaiu whites might pmdnoo the progeny ^v-ith coloureil 

 flowers, as in the chussical example of Sweet Petx. For instance, the cruss 

 between wliite-I and white-II and its reciprocal have Ixjou done in 1915 ; 

 all J^i-offepring were found to bear whita flowers in lioth cjises, and it wius 

 the same in i^j-progeny. The crosses between nil white varieties, including 

 white-Ill also, made iu various ways agi"ee in the fact that they never give 

 rise to coloitted plants, both in F^ as well as F2, and evidently in any 

 further generation. The treatment of flowers of all these varieties by ammonia 

 vaj^xjiu- according to Miss Wheld.\le' and Shibat.v does not give j'ellow 

 reaction, indicating that they do not contain flavones. All white plants are 

 cc, beciiusc the presence of C produc33 the orange cjlom'j as above stated. 



Cross V. White- 1 X magenta and vice versa. (PI II, fig. 8 and 1). 

 ccrrbb x CCRRBB F, = CcBr Bh 



The cross, white-I x magenta and its reciprocal were made iu 1916 and 

 1917 respectively. In both i^'i-hybrids we see that magenta is almost perfectly 

 dominant to white (s. the Table of Colom-s, p. 96;. On account of veiy 

 poor germination of seeds the number of individuals is rather small, especial- 

 ly in Fi, but the actual results agi-ee fairly well with the theoretical expectation. 

 The Table IV indicates the results of the F-r and i^,-generatiou. (s. p. lOi). 



We Lave thus in F^, homozygous magentas (CCRRBB): mageutiis 

 segregatmg into .3 magentas and 1 orange {CCRfBb): magentas segi-egating 

 into .3 magentas and 1 white (CcRRBB): magentas segi-egating into 9 

 magentas, 3 oranges, and 4 whites ( CcRrBb) iu the ratio 1:1:1: 4, their 

 expected numbers being 0\S : 1-G : 1-6 : 31 respectively. Furthermore, we 

 have 5 homo- and 6 heterozygous orange?, while their theoretical numbers 

 are 3-65 and 7-30 respectively. Of 7 whites ö have produced only whites. 



1 Jottrit. of Geiidks, Vol. i, 1915, p. 113. 



2 Bot. Mag., TokyS, Vol. 23, 1915, pp. 121-122. 



