v.] IN THE THEORY OF NATURAL SELECTION. 329 



I had never observed hexamerous flowers, there v^as a single 

 plant with a few such blossoms. As these flowers are sterile 

 with the pollen of the same plant, I was obliged to fertilize 

 it with pollen from another plant bearing only pentamerous 

 flowers, in order to obtain seeds from the former. For three 

 weeks I examined all the flowers from a plant grown from such 

 seed, finding 145 pentamerous, 103 hexamerous, and 13 hepta- 

 merous flowers. I examined similarly the flowers of another 

 plant produced from seed obtained from pentamerous flowers 

 from the same parent plants. There were 454 pentamerous 

 and 6 hexamerous flowers, and hence only i'3 per cent, of the 

 latter kind.' 



It must certainly be admitted that the large proportion of 

 abnormal hexamerous flowers depends upon heredity in the 

 instance first quoted ; but the hexamerous condition is not an 

 acquired character ; it is merely the first appearance of a new 

 innate character. It is not due to the reaction of the vegetable 

 organism under some external stimulus, for it appeared in a 

 plant exposed to conditions similar to those which acted upon 

 the other plant which only produced the normal pentamerous 

 flowers. It must therefore have resulted from the tendencies 

 which were present in the germ from which the plant itself 

 developed, either as a spontaneous change in the germ-plasm 

 or through the combination of two parental germ-plasms— a 

 combination which may lead to the appearance or the reality 

 of a new character. We know that the germ-plasm of each 

 individual is not a simple substance, but possesses a very 

 complex composition, for it consists of a number of ancestral 

 germ-plasms represented in very different proportions. Now, 

 although we cannot learn anything directly about the processes 

 of growth of the germ-plasm, and its resulting ontogenetic 

 stages, yet we do know, chiefly from observations upon man, 

 that the characters of ancestors appear in the offspring in very 

 different combinations and in very different degrees of strength. 

 This may, perhaps, be explained by assuming that in the union 

 of parental germ-plasms which takes place at fertilization, the 

 contained ancestral germ-plasms unite in different ways, and 

 thus come to grow with different strengths. Certain ancestral 

 germ-plasms will meet and together produce a double effect : 

 other opposed germ-plasms will neutralize each other; and 



