Page:Popular Science Monthly Volume 77.djvu/204

198 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 desirable 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 constant intercrossing. This work the writer believes has given a complete

 in selecting for high and for low protein content. Y, per cent, protein in crop; X, generations; h, high protein strain; l, low protein strain.

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 breeding to change the composition of maize was started in 1896 with a hazy Darwinian idea that as corn was known to vary in composition, continuous selection of extreme variations would produce a continuous change in type. A very old type—Burr's White—furnished the foundation 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 continually 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