390 Tricot yl oils Races. 



the seeds of tour seed-parents producinj^- no tricotyls 

 and those of one, 2 amongst 500 atavists. 



Silcnc conoidca, like the foregoing species, was ob- 

 tained by exchange in 1892 and gave a snigle tricotylous 

 seedling. In the following spring I had abotit as nian\' 

 tricotylous seedlings as in the previous species ; and in 

 the succeeding generation (1894) 3% tricotylous plants 

 amongst 407 seedlings from seeds of a single tricotylous 

 seed-parent. Only these 12 tricotyls were then planted 

 out; and their seeds were harvested separately in late 

 summer. In every lot I recorded from 300 to 900 seed- 

 lings and only in two cases, where the har\ est had 1)een 

 too small, so few as 200. The sowings contained, as a 

 rule, from 0.5 to 1.5% and only in one case, amongst 

 316 seedlings, 3% tricotyls. All the vigorous tricotylous 

 seedlings were planted out in such a way that the off- 

 spring of the individual seed-parents stood in grou])s. 

 Hieir seed was harvested from each seed-parent and 

 sown separately; and the proportion of tricotylous inch- 

 viduals was determined for each among 300 seedlings. 

 This proportion fluctuated, for the 26 seed-parents, l^e- 

 tween and 4.2%. The separate groups manifested no 

 relation to the .hereditary index of their several seed- 

 parents. The off"spring of parents with 0.5% and also 

 of those with 2% and 3%, had, as a rule, 0.6%. On 

 the other hand the offspring of seed-parents with a mean 

 of 1 % exhibited this mean ratio of 1 %. again, and the 

 highest figure obtained in this experiment, 4.2% oc- 

 curred amongst them. 



The maximum values in the three succeeding genera- 

 tions were therefore 3, 3 and 4%, i. e., they were fairly 

 constant. 



In Silcnc uocfiflora, also, I have studied tricotyly 



