No. 568] X CAPSELLA BURSA-PASTORIS ABACHN01DKA 199 



Whether the parent plant was of a hybrid character or 

 whether the parent plant was mutating, and the new form 

 or forms were to be looked upon as mutants, in either 

 case there existed the possibility, if not the probability, 

 that from the seeds obtained from those plants of the 

 second generation which appeared "normal," a third gen- 

 eration might be obtained which would again present the 

 abnormal form. Such indeed proved to be the case. 



The seed for the next generation was obtained from 19 

 plants. The seed was sown separately in pots of steril- 

 ized soil. Certain of the parent plants, which we now 

 identify with Shrill's simplex and rhomboidea, produced 

 a uniform, broad-leaved offspring. Others behaved like 

 the parent, the form arachnoidea appearing in 197 indi- 

 viduals out of a total of 979, which does not include the 

 713 which bred true to the broad type. (For an illustra- 

 tion of these types see Fig. 3.) 



It is unnecessary to go into details as to the various 

 theories which suggested themselves as a solution of the 



