in Pot 2 exceeding (though only by half an inch) its crossed opponent.  This victory was fairly won after a long struggle.  At first the self-fertilised plant was several inches taller than its opponent, but when the latter was 4 1/2 feet high it had grown equal; it then grew a little taller than the self-fertilised plant, but was ultimately beaten by it to the extent of half an inch, as shown in Table 2/7.  I was so much surprised at this case that I saved the self-fertilised seeds of this plant, which I will call the “Hero,” and experimented on its descendants, as will hereafter be described.

Besides the plants included in Table 2/7, nine crossed and nine self-fertilised plants of the same lot were raised in two other pots, 4 and 5.  These pots had been kept in the hothouse, but from want of room were, whilst the plants were young, suddenly moved during very cold weather into the coldest part of the greenhouse.  They all suffered greatly, and never quite recovered.  After a fortnight only two of the nine self-fertilised seedlings were alive, whilst seven of the crossed survived.  The tallest of these latter plants when measured was 47 inches in height, whilst the tallest of the two surviving self-fertilised plants was only 32 inches.  Here again we see how much more vigorous the crossed plants are than the self-fertilised.

Crossed and self-fertilised plants of the seventh generation.

These were raised as heretofore with the following result:—­

Table 2/8.  Ipomoea purpurea (Seventh Generation).

Heights of Plants in inches: 

Column 1:  Number (Name) of Pot.

Column 2:  Crossed Plants.

Column 3:  Self-fertilised Plants.

Pot 1 :  84 4/8 :  74 6/8. 
Pot 1 :  84 6/8 :  84. 
Pot 1 :  76 2/8 :  55 4/8.

Pot 2 :  84 4/8 :  65. 
Pot 2 :  90 :  51 2/8. 
Pot 2 :  82 2/8 :  80 4/8.

Pot 3 :  83 :  67 6/8. 
Pot 3 :  86 :  60 2/8.

Pot 4 :  84 2/8 :  75 2/8.

Total :  755.50 :  614.25.

Each of these nine crossed plants is higher than its opponent, though in one case only by three-quarters of an inch.  Their average height is 83.94 inches, and that of the self-fertilised plants 68.25, or as 100 to 81.  These plants, after growing to their full height, became very unhealthy and infested with aphides, just when the seeds were setting, so that many of the capsules failed, and nothing can be said on their relative fertility.

Crossed and self-fertilised plants of the eighth generation.