in SELECTION ALONE DOES NOT LEAD TO 

 THE ORIGIN OF NEW SPECIES. 



§ 7. SELECTION IN AGRICULTURE AND HORTICULTURE. 



Botanical literature affords very few instances of 

 scientific experiments on artificial selection. And so long 

 as this continues to be the case we shall be thrown back 

 on the experience of breeders. 



One of the best scientific experiments of this kind 

 is Fritz Mueller's on Selection in Maize. ^ He dealt 

 with the number of rows on the ears (Fig. 17) and 

 started by choosing the ears with the greatest number 

 of rows for sowing; the commonest were those with 

 10-12 rows; the others group themselves round this fig- 

 ure in familiar fashion according to Quetelet's laws. 

 Among many thousands of ears a single one was found 

 with 18, but none with 20 rows. At the end of three 

 years selection the mean had shifted to 16 rows, while 

 single ears had as many as 26 rows. 



I have repeated this experiment over a longer series 

 of vears, and have exhibited the result in the form of a 

 genealogical tree, plotting the variability by the fan 

 method as explained in Fig. 13, p. 52. The fans have been 

 reduced by substituting the most essential lines for the 

 numerous triangles of Fig. 13. The middle line of each 



^Kosmos, i886, Vol. II, p. 22. 



