Bennet Mills Allen 141 



Conclusions. 



1. The sex cords — medullary cords and seminiferous tubules — are 

 homologous structures formed as tubular invaginations of the peritoneum. 



2. The cords of Pfiiiger are formed from the same source and in the 

 same manner as the sex cords, but at a slightly later period of time. 



3. The rete cords are formed at the same time as the sex cords and 

 in the same manner. 



4. The connective tissue of the sex-gland — stroma and albuginea — 

 is derived from the peritoneum. 



5. The interstitial cells of both ovary and testis are formed from 

 connective tissue in reference to a process of degeneration occurring in 

 the sex gland. 



6. The primitive sex cells seen in the earliest stages are precociously 

 developed oogonia or spermatogonia of the second order, similar cells 

 developing during later stages, from apparently undifferentiated peri- 

 toneal cells. 



7. The sex glands exert a specific influence, causing follicles to form 

 in the intra-ovarian rete of the pig, and bringing about the development 

 of spermatogonia in the intra-testicular rete of both pig and rabbit. 

 Such sex elements are not functional, because of the fact that they suffer 

 early degeneration. 



BIBLIOGRAPHY. 



Allex, B. M., 03. — The Embryonic Development of the Ovary and Testis 



of the Mammalia (preliminary account). Biological Bulletin, Vol. V, 



1903. 

 Balfour, F. M., 78.— On the Structure and Development of the Vertebrate 



Ovary. Quart. Jour. Micro. Science, Vol. XVIII, 1878. 

 Balfour, F. M., 74. — On the Development of the Elasmobranch Fishes, Urino- 



genital System. Complete Works, Vol. I, 1885. 

 Beard, J., 03. — The Germ-cells of Pristiurus. Anat. Anz., Bd. XXI, 1903. 

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 Beard, J., 00. — The Morphological Continuity of the Germ-cells in Raja batis. 



Anat. Anz., Bd. XVIII, 1900. 

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Bd. 1902. 

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Gesellsch. 3 Versam., 1 Sitz., 1889. 

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XXX, 1887. 

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