The Production of New and Improved Varieties of Timothy 361 



the average yield of the seedlings from the same five individuals repre- 

 sented by the corresponding dots on the solid line. 



From a study of this graphical illustration of the comparative average 

 yields, it will be seen clearly that as the yield of the clons of an individual 

 increases, there is also, in general, an increase in the average yield of the 

 inbred progeny of these individuals. It is also interesting to note that the 

 average yield of the inbred progeny does not increase nearly so rapidly 

 as does the yield of the clonal plants ; in other words, there is considerable 



15 



17 



16 



\5 



14 



IS 



12 



II 



10 



9 





 o 



7 



6 



5 



4 

 3 

 2 

 / 

 



Fig. 92.- — Diagram shelving the comparative yields of 100 different types grown 

 as clonal varieties, with the same types grown from inbred seed. Black 

 line — clonal yields; broken line — yields by seed propagation 



regression in the yield of the progeny. This is also shovim in the com- 

 parative transmission of yields of ten light- and ten heavy -yielding plants, 

 as appears in Table i. Here it will be seen that, in general, the ten lightest- 

 yielding original plants have given rather heavier-yielding progenies; 

 the regression being positive and toward the mean yield of the species, 

 which is much greater than the yields of these ten plants, selected as 

 extreme illustrations of light yielders. In the ten heavy-yielding plants, 

 selected as extremes of this character, the progeny yields are much below 

 the yields of the original plants, there being a marked negative regression 

 toward the mean yield of the species. 

 19 



