iq8 



THE POPULAR SCIENCE MONTHLY 



for the prosecution of the work, but are all based upon the idea of 

 proving the capacity of a mother ear by the characters of the progeny 

 produced. If a very large number of ears are included in the original 

 stock, it is unquestionable that some of them will transmit more de- 

 sirable characters than others. It only remains to test them out by 

 growing the seed of each ear in marked plots or rows and gradually 

 eliminating the undesirable types. 



The accompanying diagrams, showing the work of the Illinois 

 Agricultural Experiment Station in their experiments in selecting 

 for high and low protein content, and high and low oil content, 

 admirably illustrate the rapidity with which progress can be made 

 by selecting only from the maternal side, even in the face of con- 

 stant intercrossing. This work the writer believes has given a com- 



Y 



8 



7 

 6 

 5 

 4 

 3 



X 



s 



10 11 



Pig. 3. Diagrammatic representation of the Results of the Illinois Agri- 

 cultural Experiment Station in selecting for high and for low protein content. 

 T ' , per cent, protein in crop ; X, generations ; h, high protein strain ; I, low protein 

 strain. 



plete corroboration of Johannsen's conclusions on pure lines. This 

 interpretation has been made, however, from their published data, and 

 the Illinois station should not be held responsible. This work of breed- 

 ing to change the composition of maize was started in 1896 with a hazy 

 Darwinian idea that as corn was known to vary in composition, con- 

 tinuous selection of extreme variations would produce a continuous 

 change in type. A very old type — Burr's White — furnished the foun- 

 dation stock. A chemical analysis was made of parts of the individual 

 ears each year, and the extreme ears planted. From the first, the four 

 lines above mentioned were planted in isolated plots and were continu- 

 ally selected in the same direction. After ten generations the average 

 crop of the high protein line had reached 14.26 per cent., while the low 

 protein line was only 8.64 per cent.; the high oil strain had reached 

 7.37 per cent., while the low oil strain was reduced to 2.66 per cent. 

 These facts clearly show the rapidity with which results can be obtained 



