THE MULTIPLE TESTIS OF URODELES. 67 



6. The multiple testis is clearly but a result of the spermato- 

 genetic pattern of the species possessing it. 



7. Modifications of the spermatogenetic pattern cause differ- 

 ences in the number or size of the testicular lobes even in animals 

 of the same age. Even in the individual the two organs, from a 

 similar cause, may occasionally be of different type. 



8. Neither the multiple testis nor the peculiar combination of 

 factors producing it are regarded as of important phylogenetic or 

 adaptative significance. 1 



LITERATURE CITED. 

 Champy, C. 



'12 Recherches sur la spermatogenese des batraciens et les elements ac- 



cessoires du testicule. Archiv. d. zool. exper., T. 52, p. 13. 

 Duvernoy, G. L. 



'51 Fragments sur les organes genito-urinaires des Reptiles et leur produits. 

 3. fragment : Sur 1'appareil de la generation chez les males plus particu- 

 lierement, et chez les femelles des Salamandres et des Tritons. Mem. 

 Acad. Sc., T. u, pp. 17-74; appendix to same, pp. 75-95. 

 Hoffmann, C. K. 



'73-78 Dr. H. G. Bronn's Klassen und Ordnungen des Thierreiches. 6 



Bd., 2 Heft: Amphibien, p. 449. 

 Humphrey, R. R. 



'21 The Interstitial Cells of the Urodele Testis. Am. Jour. Anat, Vol. 



29, P. 213. 

 Kingsbury, B. F. 



'02 The spermatogenesis of Desmognathus fusca. Am. Jour. Anat., Vol. 



i, P- 99. 

 Kingsbary, B. F., and Hirsh, Pauline E. 



'12 The Degenerations in the Secondary Spermatogonia of Desmognathus 



fusca. Jour. Morph., Vol. 23, p. 231. 

 McGregor, J. H. 



'99 The Spermatogenesis of Amphiuma. Jour. Morph., Vol. 15, supp., 



P- 57. 

 Spengel, J. W. 



'76 Das Urogenitalsystem der Amphibien. I. Thiel. Der Anatomische 



Bau des Urogenitalsystems. Arbeiten aus dem zoolog.-zootom. In- 



stitut in Wiirzburg. 3 Bd., i. Heft, s. 1-114. 

 von Wittich. 



'53 Beitrage zur morphologischen und histologischen Entwickelung der 



Harn- und Geschlechts-werkzeuge der nackten Amphibien. Zeitsch. 



fur wissensch. Zool., 4 Bd., s. 125-167. 



i The writer takes pleasure in acknowledging the helpful suggestions and 



criticisms offered by Dr. B. F. Kingsbury, and the courtesy of the Harvard 



Museum of Comparative Zoology, from whose library the publications of 

 Spengel were obtained. 



