106 LOCK : PRESENT STATE OF 



other plants) with this distribution of the pigments reversed. 

 Other plants again bear pods which are only very faintly 

 pigmented. In addition to these types, the pigmented 

 areas may be uniform or more or less broken up into 

 patches. 



The great amount of individual fluctuation renders it often 

 impossible to place a particular plant in one or other of the 

 ten presumptive classes thus indicated, and the complete 

 elucidation of the phenomena is thus rendered very difficult, 

 if not impossible. On the whole, fche evidence must be taken 

 to indicate that segregation is going on between several pairs 

 of independent factors. 



5. — The Presence or Absence of Fasciation. 



Mendel quite properly described the non-fasciated character 

 as dominant. He also described normal segregation, and this 

 description is also piobably correct. 



In my own experiments, when every plant of F 2 which 

 showed any sign of fasciation was counted as recessive, segre- 

 gation was found to take place in the proportion of 3 : 1 

 approximately. But very many of the fasciated plants in F 2 

 showed this modification to a very much slighter extent than 

 their fasciated grandparent, the Irish Mummy pea. Some of 

 this difference is undoubtedly to be ascribed to the effect of 

 crowding and bad conditions of growth, since the fasciated 

 plants of F 2 had to compete with thrice their number of normal 

 sister plants, but it did not seem likely that this would account 

 for the whole difference. 



Seeds of very slightly fasciated plants of F2 were therefore 

 sown to produce a third generation, F 3. The seeds were sown 

 at wide intervals, and the summer (1907) was very wet. All 

 the plants produced in every case were fully fasciated — almost, 

 if not quite, as much so as the plants of the original parental 

 stock. It would seem as if the fasciated character is one which 

 \s, especially susceptible to the influence of the environment. 

 Other evidence exists which goes to show that fasciation is a 

 character of which the development depends to a very large 

 extent upon the influence of external conditions. 



