222 GENETICS IN RELATION TO AGRICULTURE 



In one F 2 population of 255 plants Lotsy was able to distinguish about 

 twenty-five different flower types as shown in Fig. 98. The flower 

 types were not distinct, but represented merely different steps in an 

 almost continuous series, save for the discontinuity incident upon the 

 sharp segregation of a group of plants which bore peloric flowers. More- 

 over, within any of these flower types the plants differed greatly in a 

 number of other characters, such as size, color of flower, form of leaf, 

 habit of growth, etc. As regards fertility there was segregation into 

 self-fertile and self-sterile plants, the former being in the majority. Of 

 the 255 plants, 135 produced zygomorphic flowers, 119 peloric flowers, 

 and one plant produced both zygomorphic and peloric flowers. In 

 color the flowers on different plants ranged from the deep red of the majus 

 parent to the pale color of molle. 



Lotsy also grew several F 3 populations. One of these from an F 2 

 plant bearing hooded zygomorphic flowers consisted of 209 plants all 

 of which were different, indicating again an extreme condition of hetero- 

 zygosity. Not a single plant produced flowers displaying the hooded 

 character of the parent plant. There was again a vast array of flower 

 forms, twenty-three different types being represented. With respect 

 to the peloric condition, 113 plants bore peloric flowers only, 94 zygo- 

 morphic flowers, and 2 bore both types. Although several different 

 colors were represented, Lotsy was able to arrange them in two classes; 

 the first consisting of 153 plants approximating the red color of majus, 

 and the second group of 56 plants of about the color of the pale molle 

 parent. There was, therefore, a fair indication of Mendelian segrega- 

 tion for color in this generation. 



In this population as shown in Fig. 99 a plant was obtained which 

 very closely resembled the type of A . molle in all its characters, and re- 

 produced these characters in its progeny. Other plants were obtained 

 which strongly resembled majus in certain of their characters, but not so 

 completely throughout. The important feature here is the fact that 

 even in F 2 segregation and recombination of factors have produced a 

 plant which is practically identical with one of the parents. 



Other F 3 populations were grown from F 2 plants displaying different 

 sets of characters. One of these from a zygomorphic F z plant produced 

 a population segregating for color and form (zygomorphic vs. peloric) of 

 flower. Another population from a peloric F z plant consisted entirely of 

 peloric flowering plants, but in this population there were many different 

 color classes. An F z plant of the pale color of molle gave an F 3 popula- 

 tion consisting entirely of pale-flowering plants but showing segregation 

 in form and for the peloric character. 



Obviously if results such as these are to be explained on a Mendelian 

 basis, it must be assumed that a relatively large number of factor differ- 



