MALE GENERATIVE ORGANS. 739 



ureters, and also, as we shall immediately see, of the sexual passages : 

 no urinary bladder is as yet developed, nevertheless vestiges of its 

 appearance begin to become visible. The cloaca is, in fact, in some 

 birds divided into two compartments, distinct both in their appearance 

 and in their office ; these, moreover, are separated by a constriction, 

 more or less well-defined in different species. It is into one of these 

 compartments that the rectum opens, while the other (fig. 368, m m) 

 contains the orifices of the ureters and generative canals ; the latter is 

 therefore generally distinguished by the name of the urethra -sexual 

 portion of the cloaca, and is in truth a remnant of the allantois, and a 

 rudiment of a bladder for the accumulation of the urine. 



(2093.) An unctuous secretion, peculiar to the class under considera- 

 tion, has been provided for the purpose of oiling the feathers ; and in 

 water-birds the fluid alluded to becomes of very great importance to 

 their welfare, as it causes their plumy covering to repel moisture so 

 efficiently that it is never wet. The gland given for this purpose is 

 called the " uropygium" and is situated upon the back of the os coc- 

 cygis; from this source the bird distributes the oily material thus 

 afforded to all parts of its plumage. 



(2094.) The male generative organs in Birds are fully as simple in 

 their structure as those of the Reptilia. The testes are two oval bodies 

 (fig. 368, #), invariably situated in the lumbar region, lying upon the 

 anterior portion of the kidney. In their intimate structure they con- 

 sist of contorted and extremely slender tubes, wherein the semen is 

 elaborated, contained in a strong capsule. The sperm-secreting tubules 

 of each testis terminate in a slightly flexuous v as deferens (h, f), that 

 opens into the cloaca by a simple orifice (m m). In most birds it can 

 scarcely be said that a penis exists at all, two simple rudimentary vas- 

 cular papilla} at the termination of the vasa deferentia constituting the 

 entire intromittent apparatus ; so that copulation between the male and 

 female must, in the generality of species, be effected by a simple juxta- 

 position of the sexual orifices : nevertheless in the web-footed tribes, 

 which copulate in the water, and in the Ostrich, the penis of the male is 

 much more perfectly organized, as will be seen by the following descrip- 

 tion extracted from Cuvier*. 



(2995.) The structure of the penis is far from being the same in all 

 birds provided with such an organ ; it offers, in fact, two types extremely 

 different from each other, whereof the Ostrich and Drake may be taken 

 as examples. The penis of the Ostrich is of a size proportioned to that 

 of the bird. Its form is conical ; and a deep, narrow groove runs along 

 its upper surface from the base to the point. The vasa deferentia open 

 into the cloaca opposite to the commencement of the groove ; so that the 

 semen flows directly into this furrow. This penis consists, first, of two 

 solid conical bodies, entirely composed of fibrous substance, supported at 

 * Le9ons d'Anat. Comp. torn. v. p. 108. 



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