184 EEPRODUCTION IN PLANTS AND ANIMALS. 



and all the rest are tie result of hybridization, then there 

 is no limits to species and no permanence whatever in their 

 characters. This, however, is not borne out by facts. It 

 is necessary in order to conception, not only that the pollen 

 or sperm should reach the vegetable or animal ovule, but 

 also that there should be some harmony of relation between 

 the germ and the nature of the fecundating element, other- 

 wise vivification will not ensue. Thus, notwithstanding the 

 mixture of the fluid of the milt of different male fishes in 

 the same waters, where there are dispersed so many different 

 species of eggs, hybrids amongst them are rare; in like 

 manner, each dioecious plant develops only on the stigmas of 

 its pistils, the pollen of its true species, from amongst so 

 many other kinds of pollen carried by the same winds. It 

 is thus that the character of each species is perpetuated in 

 its native purity. 



Most plants are hermaphrodite, that is to say, the male 

 and female are united in the same individual. Thus in the 

 majority of flowers the stamens surround the pistils on a 

 common support, as in the lily and geranium, or they may 

 be developed apart from each other, in separate flowers on 

 the same plant, as in the Indian com and mock-orange. 

 In this last instance the plants are said to be monoecious. 

 Some animals are also hermaphrodite, such as muscles, oys- 

 ters, zoophytes ; in fact, among all the immovable mollusca 

 and radiata which approach so closely in functions and 

 habits to plants, hermaphrodism prevails, which is the most 

 common manifestation of sexuality in the vegetable world. 



