VIRGINAL REPRODUCTION. 197 
one of two generative substances, either the male or the 
female. The female individuals, both in animals and plants, 
produce eggs or egg-cells. The eggs of plants in the case 
of flowering plants (Phanerogama), are commonly called 
“embryo sacs”; in the case of flowerless plants (Crypto- 
gama), “fruit spores.” In animals, the male individual 
secretes the fructifying sperm (sperma); in plants, the 
corpuscles, which correspond to the sperm. In the Phane- 
rogama, these are the pollen grains, or flower-dust ; in the 
Cryptogama, a sperm, which, like that of most animals, 
consists of floating vibratile cells actively moving in a 
fluid—the zoosperms, spermatozoa, or sperm-cells. 
The so-called wirginal reproduction (Parthenogenesis) 
offers an interesting form of transition from sexual repro- 
duction to the non-sexual formation of germ-cells (which 
most resembles it); it has been demonstrated to occur in 
many cases among Insects, especially by Siebold’s ex- 
cellent investigations. In this case germ-cells, which 
otherwise appear and are formed exactly like egg-cells, 
become capable of developing themselves into new indi- 
viduals without requiring the fructifying seed. The most 
remarkable and most instructive of the different partheno- 
genetic phenomena are furnished by those cases in which 
the same germ-cells, according as they are fructified or not, 
produce different kinds of individuals. Among our common 
honey bees, a male individual (a drone) arises out of the 
eggs of the queen, if the egg has not been fructified; a 
female (a queen, or working bee), if the egg has been fructi- 
fied. It is evident from this, that in reality there exists 
no wide chasm between sexual and non-sexual reproduc- 
tion, but that both modes of reproduction are directly 
