Not only is this the case, but it may he proved by many observations that the normal or type to which the average children of exceptional parents tend to revert may itself be rapidly modified.
In proof of this I refer to the following experiments in selection by Fritz Müller (Ein Zuchtungs-versuch an Mais. Kosmos, 1886, 2, i, p. 22):
Yellow corn is very variable in many respects. The number of rows of kernels on the cob is usually from eight to sixteen; cobs with ten or twelve rows being the most common, while one with eighteen or twenty rows is very seldom found. After searching through several hundred cobs Fr. Müller found one ear with eighteen rows, but none with more.
In 1867 he sowed, at different times, and in such a way as to prevent crossing, (1) seed from the cob with eighteen rows; (2) the seed from the finest sixteen-rowed ear; and (3) the seed from the finest fourteen-rowed ear. In 1868 he sowed (1) seed from a sixteen-rowed ear which had grown from seed from a sixteen-rowed ear; (2) seed from an eighteen-rowed ear from sixteen-rowed seed; and (3) seed from an eighteen-rowed ear from eighteen-rowed seed. In 1869 he sowed (1) seed from an eighteen-rowed ear with eighteen-rowed parents and grandparents; (2) seed from a twenty-rowed ear with eighteen-rowed parents and grandparents; and (3) seed from a twenty-two-rowed ear from seed from an eighteen-rowed ear produced from seed from a sixteen-rowed ear. The results are given in the accompanying table:
| Number of rows on cob from which seed were taken. | 1867. | 1868. | 1869. | ||||||
| 14 | 16 | 18 | 16 16 |
16 18 |
18 18 |
18 18 18 |
18 18 20 |
18 18 22 | |
| Total number of cobs produced. | 658 | 385 | 205 | 1,789 | 262 | 460 | 2,486 | 740 | 373 |
| Per'ct | Per'ct | Per'ct | Per'ct | Per'ct | Per'ct | Per'ct | Per'ct | Per'ct | |
| 8-rowed cobs | 0·3 | . . . . | 0·5 | 0·1 | . . . . | . . . . | . . . . | . . . . | . . . . |
| 10-rowed cobs | 14·4 | 3·0 | 1·0 | 1·4 | 0·8 | 0·2 | 0·1 | . . . . | . . . . |
| 12-rowed cobs | 48·0 | 22·8 | 13·0 | 22·6 | 14·5 | 7·8 | 6·1 | 6·1 | 2·7 |
| 14-rowed cobs | 35·6 | 48·6 | 37·8 | 48·5 | 46·7 | 35·4 | 37·3 | 28·5 | 25·3 |
| 16-rowed cobs | 3·2 | 18·7 | 34·5 | 22·2 | 23·7 | 33·8 | 33·5 | 41·6 | 41·8 |
| 18-rowed cobs | 0·5 | 6·8 | 12·6 | 4·9 | 12·3 | 18·2 | 18·6 | 20·2 | 24·1 |
| 20-rowed cobs | . . . . | 0·1 | 0·3 | 0·3 | 1·2 | 4·4 | 3·9 | 2·8 | 4·8 |
| 22-rowed cobs | . . . . | . . . . | 0·3 | . . . . | 0·8 | 0·2 | 0·5 | 0·8 | 1·0 |
| 26-rowed cobs | . . . . | . . . . | . . . . | . . . . | . . . . | . . . . | . . . . | . . . . | 0·5 |
| Average | 12·61 | 14·08 | 14·9 | 14·15 | 14·39 | 15·52 | 15·57 | 15·70 | 16·15 |
It will be seen from this table that the number of ears with few rows decreases very rapidly in plants grown from seed taken
