432 Tricotyloiis Races. 



tetracotjv'lous parent with 31% were planted out. Ilere 

 again both the tricotylous and tetracotylous plantlets were 

 used, but this time not in separate lots Seeds of Z7 

 plants were saved and sown, and they gave values which 

 did not differ essentially from those obtained in the fore- 

 going year. They were distributed fairly regularly be- 

 tween 16 and 52% and had a mean of 35%, i. e., the 

 mean vahie had undergone a considerable increase. 



Antirrhinum niajns. It was with this plant that I 

 made one of my first experiments in the production of 

 tricotylous races, and the fact that the progress in this 

 case was much slower than in later cultures, may well 

 Ije ascribed to the less extensive experience which I had 

 at that time. I am now inclined to regard the practice 

 of selecting from an insufficient number of seed-parents, 

 and also of inadequate manuring as some of the causes. 

 Nevertheless I shall describe the experiment because it 

 ultimately led to a genuine tricotylous race. On the other 

 hand it may not be unimportant to show that, if a repe- 

 tition of my tricotylous cultures is made, the attainment 

 of the end must not always be expected to be reached 

 in two or three generations. 



I have attempted to isolate tricotylous races from two 

 varieties of the Snap-dragon. First from tlie striped 

 variety mentioned on page 120 of this volume, and figured 

 in Plate I; but as the success attamed with this after 

 four generations (1892-1896), was not so great as in 

 the other case, and 45% had not been exceeded, I did 

 not proceed further with it. Therefore I shall confine 

 my description to the latter. It was a dark red half- 

 dwarf variety. 



In 1892 I had four tricotylous plants from bought 

 seed, and from their seeds obtained in the following 



