Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 female gene- N FIG. 94.—Generative appara- tus of a rhabdoccee Tur- bellarian (vortex viridis) (after M. Schultze). T, tes- tis; Vd, vas deferens; Vs, seminal vesicle ; P, pro- trusible penis; OB, ovary; Va, vagina ; M, uterus ; D, yolk gland ; Rs, recep- tacnlmn serninis. and rative organs in different indivi- duals the most complete form of sexual reproduc- tion, so far as con- cerns division of labour, is reached; but at the same time a progressing dimorphism of the male and female in
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 female gene- N FIG. 94.—Generative appara- tus of a rhabdoccee Tur- bellarian (vortex viridis) (after M. Schultze). T, tes- tis; Vd, vas deferens; Vs, seminal vesicle ; P, pro- trusible penis; OB, ovary; Va, vagina ; M, uterus ; D, yolk gland ; Rs, recep- tacnlmn serninis. and rative organs in different indivi- duals the most complete form of sexual reproduc- tion, so far as con- cerns division of labour, is reached; but at the same time a progressing dimorphism of the male and female individuals be- comes apparent. This is due to the fact that the or- ganization in bi- sexual animals is more and more influenced by the deviating func- tions of the sexual organs, and with FIG. 95.—Generative appa- ratus of the medicinal leech. T, testis ; Vd, vas deferens ; Nh, vesicula seminalis; Pr, prostate ; C, penis ; OB, ovaries with vagina and female generative opening. the increasing complication of sexual life becomes modified for the performance of special accessory functions connected with the production of ova and spermatozoa. In the first place, the modification of the generative ducts of the two sexes in accordance with the function they have to perform determines the development of secondary sexual characters and of sexual dimorphism. Other organs as well as the generative appa-
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