MALE ORGANS OF BIRDS. 



245 



pointed processes, which, in the Gander, are arranged in transverse 

 rows on either side the urethral groove, d, and near the extre- 

 mity of the penis are inclined backward. The elastic band, b, b, has 

 been cut open lengthwise in the figure given by Home :^ it is 

 surrounded by cavernous tissue, and terminates in the blind end 

 of the sac which can be everted. A groove, ib. d, d, commencing 

 Avidely at the base, follows the spiral turns of the sac to its termi- 

 nation : the sperm-ducts open upon papillte at the base of this 

 groove. This form of penis has a muscle by which it can be 

 everted, protruded, and raised. 



The base of the penis in the Ostrich is attached to the fore wall 

 of the cloaca, the conical body is bent in a recess, out of wliich it 

 can be drawn and into which it can be returned by muscles. It 

 consists of two solid fibrous bodies, the fissure between which is 

 covered by cavernous erectile tissue, bounding the seminal groove ; 

 but it has no evertible sacciform part : there is a third elastic sub- 

 stance internal to the cavernous substance which produces the 

 twisted form. 



The Drake's penis is formed after the type of that of Lizards 

 and Serpents. The Ostrich's penis is like that of the Tortoise 

 and Crocodile.^ 



120 



121 



122 



Siiermatozoa of the Cork (Gallus 

 domestictis) . cccvi. 



Sperm-cell with pperniatoa. 

 Sparrow. Ib. 



Sperm-cell with spermatozoa. 

 Cock. Ib. 



The spermatozoa of Birds, like those of Lizards, have 



cylindrical body; generally straight or wa^■y, 

 obtuse anteriorly, and tapering behind into a fihx- 

 mentary tail of varying length according to tlic 

 species, fig. 120; but in the Cantor es the body 

 is tmsted spirally in three to five or more turns, 

 pointed anteriorly and terminating in a usually 

 long filamentary tail, fig. 123. The sperm-cell 

 contains many spermatoa, fig. 121, and in these the 

 spermatozoa are developed and usually excluded 



^ xxvir. and Pbil. Trans. 1802. 2 ^-^^ 



