1877. ] BURSA FABRICII IN BIRDS. 317 
constriction into D, the cavity B D thus formed receiving the aper- 
ture of C. In such a form as Plotus, where the opening is but very 
slightly constricted, we have a type connecting the two extremes ; 
and I have seen Rhea in a stage very similar to that mentioned above 
in Cygnus olor. In confirmation of this view as to the true relation 
of these parts, in the Ostrich &c. the lower part of the bursa, in 
the region corresponding to D in figs. 8 and 9, is not glandular (vide 
fig. 6, p. 315, where the non-glandular part of the bursa is seen 
beneath pores H H'). 
Fig. 8. Fig..9. 

Diagram showing two chief Types of Development of the Bursa Fabricii. 
R. Rectum. 3B, Bursa. C. Cloacal chamber. D. Lowest chamber of “ cloaca.” 
d, Openings of urino-genital ducts. 
With regard to the function and homologies of the bursa Fabricii, 
great differences have prevailed amongst authors. Thus Milne- 
Edwards says’, “Fabrice d’Acquapendente, 4 qui lon doit la 
découverte de cette bourse, la considérait comme un réservoir séminal, 
tandis que d’autres naturalistes* la regardent comme une vessie uri- 
naire. Perrault et quelques auteurs modernes® y voient l’analogue 
des glandes anales des Mammiféres, et Geoffr. St.-Hilaire l’assimile’ 
aux glandes du Cowper’; enfin, M. Martin St.-Ange la compare 4 
la prostate.” Emil. Huschke, in the paper mentioned above, has 
studied its development, and, after a comparison of the organs of 
similar appearance, is inclined to consider it as the primitive uri- 
nary vesicle of the Wolfian bodies, from the fact that the ducts of 
this gland take origin from just that part of the cloaca which after- 
wards assumes the form of the bursa. Harvey and others have 
sufficiently disproved Fabricius’s ideas as to its serving as a spermo- 
theca; nor can the bursa be regarded as a urinary bladder,—first, 
because it is not devoted to containing the urine; secondly, because 
in other Sauropsida and also in the Mammalia the urinary bladder is 
ventral, not dorsal, in position. For a similar reason, as well as from 
the fact that they are paired organs, the ‘“‘burse anales” of the 
1 Phys. et Anat. Comp. vol. viii. p. 514. 
® E.g. Berthold, Acad. Cxs.-Leop. Nova Acta, xiy. p- 917, 1828, and Geoffroy 
St.-Hilaire, Mém, du Muséum, 1823, t. ix. p. 394. 
8 FH. g. Carus, ‘ Zootomia.’ 
* Tiedemann, ‘Anat. der Vogel,’ 1810. 
