Tlie ])rogres.s of Genetics since the rediscovery of Mendel's papers. 



389 



When such a case is compared with those met with in animals 

 a close resemblance is perceptible in the fact that in both groups of 

 cases we are concerned essentially with a development of pigmenta- 

 tion, the quality, concentration, and distribution (pattern) of which 

 is decided by additional co-existing factors. There is however one 



15; 49 



Fig. 15. Diagram of the distribution of allelomorphs in F.) from the cross between 

 white sweet-pea, long-pollened X white, round-pollened. Colour is due to meeting 

 of C with E. If B is absent the colour is red; if B is present the Hower is purple. 

 There are thus 27 purple : 9 red : 28 white. Coloured : white are thus 9:7. — The 

 line of figures at the foot shows the ratio of long-pollened to round-pollened in each 

 column. These peculiar ratios arise from jmrtial coupling- between B and the long- 

 pollen character (see p. 396j. 



Striking diiference between the animal and the plant phenomena, 

 inasmuch as the union of two albinos in the plant may give a co- 

 loured Fj, whereas no such phenomenon has yet been authenticated 

 among animals. The flower-colour in short has, at least in the Sweet 

 Pea (and Stocks), been broken into two parts of which neither alone 



