Pot 3 :  20 6/8 :  19 2/8. 
Pot 3 :  20 2/8 :  13 2/8. 
Pot 3 :  20 6/8 :  18.

Pot 4 :  25 3/8 :  23 2/8. 
Pot 4 :  24 2/8 :  23.

Pot 5 :  20 :  18 3/8. 
Pot 5 :  27 7/8 :  27. 
Pot 5 :  19 :  21 2/8.

Total :  328.75 :  293.13.

The fifteen crossed plants here average 21.91 inches, and the fifteen self-fertilised plants 19.54 inches in height, or as 100 to 89.  These plants did not differ in fertility, as far as could be judged by the number of capsules produced, for there were seventy-five on the crossed side and seventy-four on the self-fertilised side.

Eschscholtzia californica.

This plant is remarkable from the crossed seedlings not exceeding in height or vigour the self-fertilised.  On the other hand, a cross greatly increases the productiveness of the flowers on the parent-plant, and is indeed sometimes necessary in order that they should produce any seed; moreover, plants thus derived are themselves much more fertile than those raised from self-fertilised flowers; so that the whole advantage of a cross is confined to the reproductive system.  It will be necessary for me to give this singular case in considerable detail.

Twelve flowers on some plants in my flower-garden were fertilised with pollen from distinct plants, and produced twelve capsules; but one of these contained no good seed.  The seeds of the eleven good capsules weighed 17.4 grains.  Eighteen flowers on the same plants were fertilised with their own pollen and produced twelve good capsules, which contained 13.61 grains weight of seed.  Therefore an equal number of crossed and self-fertilised capsules would have yielded seed by weight as 100 to 71. (4/4.  Professor Hildebrand experimented on plants in Germany on a larger scale than I did, and found them much more self-fertile.  Eighteen capsules, produced by cross-fertilisation, contained on an average eighty-five seeds, whilst fourteen capsules from self-fertilised flowers contained on an average only nine seeds; that is, as 100 to 11:  ’Jahrb. fur Wissen Botanik.’  B. 7 page 467.) If we take into account of the fact that a much greater proportion of flowers produced capsules when crossed than when self-fertilised, the relative fertility of the crossed to the self-fertilised flowers was as 100 to 52.  Nevertheless these plants, whilst still protected by the net, spontaneously produced a considerable number of self-fertilised capsules.

The seeds of the two lots after germinating on sand were planted in pairs on the opposite sides of four large pots.  At first there was no difference in their growth, but ultimately the crossed seedlings exceeded the self-fertilised considerably in height, as shown in Table 4/34.  But I believe from the cases which follow that this result was accidental, owing to only a few plants having been measured, and to one of the self-fertilised plants having grown only to a height of 15 inches.  The plants had been kept in the greenhouse, and from being drawn up to the light had to be tied to sticks in this and the following trials.  They were measured to the summits of their flower-stems.