472 Mutations 



ters have as yet not been ascertained in the case 

 of our toad-flax. 



In order to save seed from isolated plants it is 

 necessary, for this reason, to have at least two 

 individuals, and these must belong to the two 

 physiologically different types. Now in the 

 year 1892, as in other years, my plants, though 

 separated at the outset by distances of about 20 

 cm. from each other, threw out roots of far 

 greater length, growing in such a way as to 

 abolish the strict isolation of the individuals. 

 Any plot may produce several stems from such 

 roots, and it is manifestly impossible to decide 

 whether they all belong to one original plant or 

 to the mixed roots of several individuals. No 

 other strains were grown on the same bed with 

 my plants however, and so I considered all the 

 stems of the little group as belonging to one 

 plant. But their perfect fertility showed, ac- 

 cording to the experience described, that there 

 must have been at least two specimens mingled 

 together. 



Returning now to the seeds of this pair of 

 plants, I had, of course, not the least occasion 

 to ascribe to it any higher value than the har- 

 vest of former years. The consequence was 

 that I had no reason to make large sowings, and 

 grew only enough young plants to have about 

 50 in bloom in the summer of 1894. Among 



