HEEMAPHRODITISM. 395 



Just as the lowest Plant Animals exhibit this most 

 simple origin of the complex phenomena of reproduction, 

 so, in the second place, they reveal the highly important 

 fact, that the earliest and most primitive sexual relation 

 was hermaphroditism, and that the separation of the sexes 

 originated from this only secondarily (by division of labour). 

 Hermaphroditism is prevalent in lower animals of the most 

 different groups; in these, each single individual, when 

 sexually mature, each person, contains male and female 

 sexual cells, and is, therefore, capable of self-fertilization 

 and self-reproduction. Thus, not only in the lowest Plant 

 Animals just mentioned (the Gastrseads, Chalk-sponges, 

 and many Hydroid Polyps) do we find egg-cells and 

 sperm-cells united in one and the same person ; but 

 many Worms (for example, the Ascidians, Earth Worms 

 and Leeches), many Snails (the common garden Snail), and 

 many other invertebrate animals are also hermaphrodite. 

 All the earlier invertebrate ancestors of man, from the 

 Gastrseada up to the Chordoma, must also have been her- 

 maphrodite. So, probably, w^ere also the earliest Skulled 

 Animals (Figs. 52-56, e, h, vol. i. p. 25G). One extremely 

 weighty piece of evidence of this is afforded by the remark- 

 able fact, that even in Vertebrates, in Man as well as other 

 Vertebrates, the original rudiment of the sexual organs is 

 hermaphrodite. The separation of the sexes {Gonocho- 

 rism), the assignment of the two kinds of sexual cells 

 to different individuals, originated from hermaphroditism 

 only in the farther course of tribal history. At first, male 

 and female individuals differed only in the possession of the 

 two kinds of cells, but in other respects were exactly alike, 

 as is now the case in the Amphioxus and the Cyclostoma. 



