B I R' 



ef BirJs,jK'- 4-. "•' tl>e vsrge of the fundament furrourd.-c1 by 

 fcatScrs ; M the urethra, or fcminal canal laid open throui^h- 

 out ts wlu.le extent ; cc the orificis of the vafa deferentia ; 

 liJ li\e exti-r'.ial tunic of the penis laid open, and from iu 

 elafticity thrown into ferpentine folds. 



It defervcs to be mentioned, that Blafius alfo fiip- 

 pofcd the vnfa deferentia of the tirnie terminated in the 

 penis, although he fpoke doubtingly, not having aaually 

 traced them thither. See Anatome animalium Gerardi 

 Blafii. . ^ , . , 



In the gander, fiuan, cajfuwarj, and other birds which 

 we have examined, the channel that runs upon the ex- 

 ternal part of the penis fupplies the place of the urethra, r.nd 

 appiars ftilly competent to anfwer the purpofe of a conduit 

 to the fcmen, when it is introduced into the organs of the 

 female. 



Bcfides the mucous follicles furrounding the termination 

 of the ureters and feminal dufls, there are fome others much 

 larger upon the margin of the anus, on each fide of the bafe 

 of the penis. In the gander we have noticed twelve of thcfe, 

 fix on each fide. They appear like mafies of fat lying under 

 the inner membrane of the intelHne. The three outer 

 glands have wide orifices which lead to a cavity within of 

 fomc fize ; they furnifli fpecimens of finiple mucous fol- 

 licles, a greater fize than are almoll ever met with, even 

 amongft the largtft animals. See Plate VII. in the Anatomy 

 of Birch, fig. 3. eec the large follicular glands on the margin 

 of the aniis of the gander ; fffihe three fmaller glands next 

 the penis. The anal glands are very remarkable in the 

 ta^ozvary. 



No chemical analyfis of the femen of birds has yet been at- 

 tempted. The undertaking will be attended with fomc 

 difficulty, from the fmall quantity which can be coUcded 

 for jnve (ligation. 



Female Parts of Generation. 

 There are no parts of the llrufture of birds which deviate, 

 more from that of mammalia, than the female organs of ge- 

 neration : not only their conftruftion, but their funftions, 

 differ fo much, that the fame names cannot be ap- 

 plied to each, without extending ai^alogy beyond what is 

 )uilifiablf. The genital organs of the female bird ftriilly 

 confift but of two parts, an ovary and ovarian lube ; for the 

 different portions of the latter, which have received the 

 names of uterus and vagina, perform very different funftioiis 

 from the fame parts in other animals. 



The ovary of birds is always fingle, which is a peculiarity 

 of ftruflure hardly ever met with in the other claffes of ani- 

 mals. It is fituated OTcr the defctnding aorta, above the 

 kidnies. Inftcad of the ova being imbedded in a folid mafs, 

 as in mammalia, they are contained in membranous cyfts, 

 which are prolonged into peduncles, or footilalks, that are 

 attached to the bafis of the ovary, thus prefenting the ap- 

 pearance of a chiller, or bunch of fruit, from whence the 

 older anatomifts were in the habit of calling the ovary of 

 birds, the racemus vilcllurum. Before the ovary, however, 

 is developed, the n:diments of the eggs do not projcA be- 

 yond the furnace, but lie in clofc contaft with each other, 

 and are incloftd by the external membrane of the ovary, 

 fomcthing in the manner of the ova of fifh, or amphibia. 

 The capfnles which invell the ova e>f birds in the mature 

 ftate, appear therefore to be formrd by the txtenfion of the 

 outer membrane of the ovary, jull as the contents of a her- 

 nia obtain during their protnifion a covering of peritoneum. 

 The meii'branous bags, in which the ova are included, ad- 

 here to the proper tunic of the egg iX the anterior part only ; 

 for polleni rly thvy are quite diftindt, being prolonged into 

 a funnel, or tube, which forms the peduncle to each ovum. 



B I R 



The blood-veffcls are tranfmitted through this funnel, and 

 ramify in the fpace left between the capfulc and the back 

 part of the ovum, dillribiiting their branches in a limilar way 

 to the central artery of the eye upon the back of the cryf- 

 tallinc lens in mammalia. The capfules are extremely vaf. 

 cular at e-very part, except a certain porfon of the anterior 

 furface, which appears Hke a white ftrc-ak, or broad line. 

 ■\Vhen the eruption of the ovum takes place, this part of 

 the capfule gives way, after which the cyll appears like the 

 cup of an acorn, when the nut has been filed. The older 

 anatomiib ahr.ofl univerfally believed that the capfules of 

 the ov.-. were imperfedl at their anterior part, and that the 

 while flreak was owing to the proper tunic of the ovum be- 

 iiig adually expofcd at this place ; they defcribe the capfule 

 as bein<T extended upon the ova in a manner fimilar to the in- 

 ternal coats of the eye, and, like thtm, terminating by a 

 defined line at the anterior part. The celebrated Hurvey, 

 however, obferved that the membrane compofing the cap- 

 fules was continued over the anterior part of the ovum, at 

 which place it became very thin. The obfervatiohs we have 

 made on this fubjed: confirm the aflertion of Harvey ; we 

 have always been able to deteCl a very fine pellucid mem- 

 brane extended over the white line, which has all the appear- 

 ance of being the continuation of the capfule. The coat 

 of the capfule confifts of fevcral indiflindt layers ; and it is 

 one of thefe only which appears to pafs over the white line. 

 The foparation of the tunic of the capfules into layers is 

 probably not an original formation, but is produced by the 

 increafe which takes place in the number and fize of the 

 blood vcflcls, and therefore the part which lies over the 

 white ftreak might be confidered as more nearly rtfcmbling 

 the membrane of the capfule as it fiill exifled. There are 

 many inilanccs of parts, on changing their pofition, either 

 acquiring or lofing vafcnlarity, and becoming fo much al- 

 tered in their llruflure and appearance, that ftparatcly they 

 could not be recognized for the fame. Tlie tunica conjunc- 

 tiva of the eye affords a well known example of this fort. 



The portion of the capfule correfponding to the white 

 line, from being bereft of blood-veffels, becomes thin, is 

 eafily ruptured, and is incapable of fupporting any interu.il 

 a&ions, in confequence of injury ; we accordingly find, that 

 this part fuffers laceration when the ovum is flu'd, without 

 the leall inflammation fucceeding, or any procefs fimilar to 

 that which arifcs upon the rupture of the ovary in mam- 

 malia. There is no depofilion of new fubilance in the ca- 

 vity of the cyft, or ctrpus luteiim, formed. The lacciated 

 portions of the membrane dil'appear (probably by abforp- 

 tion), and the edges alTume the appearance of being cut, 

 the capfules become contradted a«id thickened, and remain 

 hollow, prefenting very exadlly the rcleniblanee of cups or 

 the calyces of flowers, and thence tney have been often 

 called the calyces. 



The bafe of the ovary, in which all the pedicles of the 

 ova terminate, is of a peculiar texture. It is porous and 

 tough, and feems to be compofed of an intermixture of vef- 

 fels and ftrong cellular fubilance ; it adheres firmly to the 

 parts upon which it is placed. 



The ova, during the time they remain in the ovary, 

 poffefs only the yolk and the cicatricula ; the whites and 

 the Ihell being added to them during their paffage through 

 the ovidud. Many of ihe blood-veffels .\ hich are diflri- 

 buteel brtwcen the capfule and ihc ovum, penetrate the mem- 

 brane ot the latter, iu order to lupply blood lor the nutri- 

 tion of the egg during its growth. But when the ovum 

 arrives at maturity, thele- bf-anciies degenerate, and difappear 

 entirely before tne ovum is expelled Ir.m its cyfl. 



For the illuflrdtion of the Itruclure of thcfe parts, fee 

 6 Plate 



