DISUSE AND ITS EFFECTS. 



47 



3E- 



by sheep, deer, oxen, monkeys, goats, and occasionally 

 in man. 



In mammals the oviducts become transformed into a 

 complex uterus. Other ducts belonging to the Wolffian 

 bodies are modified in a similar way, serving to convey 

 the products of the male 

 generative gland to the ex- 

 terior. 



It is somewhat remark- 

 able that each vertebrate 

 embryo possesses male and 

 female reproductive ducts ; 

 the adult male of most verte- 

 brates possesses vestiges of 

 the female ducts, whilst the 

 adult female possesses, much 

 more constantly, easily de- 

 tected remnants of the male 

 sperm-ducts. Remembering 

 that the primitive renal 

 organs are common to both _ 



FIG. 23. Ine male reproductive 

 SeXS, and as the disused organs of a Skate, with a fully- 



ureters have been utilized 

 in the male and female for 

 reproductive purposes, it ren- 

 ders their temporary co-existence in the embryo, and the 

 persistence of one or other in a vestigial form accord- 

 ing to the sex, comprehensible without invoking aid 

 from the much-disputed question of the existence of 

 a condition of primitive hermaphrodism. 



The history of the reproductive ducts in the female 



developed oviduct on the left side. 

 CE, oesophagus ; T, testis ; E, 

 epididymis (after J. D. Matthews) ; 

 P, shell-gland. 



