Both right and left testes are functional.
In C. nigrescens and in some other species a zooid may contain a pair of ovaries, a pair of testes, or an ovary and a testis, although the males, females and hermaj phrodites do not differ from one another in external characters.
The reproductive organs, both ovaries and testes, become fused together in the middle of the body.
The .- trunk contains a spacious body-cavity filled during the breeding season by the swollen ovaries, and the same is true of the tail if we substitute testes for ovaries.
If, for instance, the testes fail to develop normally, the secretion which they discharge into the blood is abnormal in character and amount, with the result that the characters of the remotest parts of the body are more or less profoundly affected.