196 



TRANSPORTATION OF THE GAMETES 



were placed may have affected their motihty, as well as their ability to survive. 

 (See Yochem, '29.) 



The above data suggest relationships in many of the vertebrates which 

 doubly assure that sperm will reach the proper site for fertilization in the 

 oviduct. One aspect of this assurance is the physiological behavior of the 

 anatomical structures of the oviduct, which may express itself by ciliary beating 

 in some instances or, in other cases, by muscle contraction. On the other hand, 



VAGINAL CANAL 



PORTION OF THE 



VAGINAL CANAL 



VAGINAL PASSAGEWAY 

 ARY BIRTH CANAL) 



UROGENITAL SINUS 



Fig. 1 14. Bifid penis of the male opossum; diagram of female reproductive tract. (A) 

 Extended penis. (After McCrady, Am. Anat. Memoirs, 16. The Wistar Institute of 

 Anatomy and Biology, Philadelphia.) (B) Female reproductive tract. 



