182 HANS RASMUSON 



As is shown in this table the facts agree well with the theoretical 

 expectations. As the numbers are small it is possible that some 

 of the plants have another constitution than that given above. Perhaps 

 one or both of the first two crosses would have given some lilac-flowered 

 plants if the numbers had been greater, and the plants II — 9 — 4 and 



II 9 5 would then have had the constitution ciaBb. Or the last 



two crosses would perhaps have given plants with white flowers and 

 red-tinged stems, and then the plants II— 9 — 6 and II— 9— 7 would 

 have been of the genotype aaBb. However, the plant II — 9^3 must 

 surely have had the constitution given in table II, as otherwise the 

 occurrence of plants with green stems in the crosses could not have 

 been explained. 



C. TINCTORIA. 



Of C. tinctoria I raised several plants which varied greatly in the 

 shape of the first leaves. Later on the leaves of all the plants were 

 practically of the same shape, and it is possible that the differences 

 between the first leaves were altogether due to external influences and 

 thus modifications. Of this character I have, however, made no gene- 

 tical investigation. 



One of the plants raised was very different from the others in 

 the colour of the leaves. These were not self green as in normal 

 plants but had yellow spots and stripes. I have crossed this variegated 

 form with a normal green and the results are given below. 



Hybridisation VI. 

 505 a, variegated, X 505 b, green. 

 Fl : 7 green plants. 

 F 2 : VI — 5 : 34 green, 10 variegated. 



The numbers in F. show that a segregation following the theore- 

 tical 3 : 1 ratio occurred. The difference between the numbers expe- 

 rimentally found and the calculated (33 and 11 + 2,906) numbers is 

 only rt 1. Thus the facts are very well in accordance with the theo- 

 retical expectations. This shows that here only one gene for self green 

 colour is involved. This is also the case in most investigated plants 

 where variegation is found. That two different genes for self colour 

 can occur, however, is shown by Ikeno in Plantago (3). 



Two of the variegated Fo-plants were self-pollinated and gave rise to 

 progenies consisting of only variegated individuals, 3 in one case and 



