GENERATION. 



Vfiung in this ftate, are denominated ov'iparouj. In mod of 

 thefe the gerra contained in the egg is not developed, or 

 hritchcd, until that part has quitted the body of the mother, 

 or has been laid ; whether it be neceflary that it flioulJ be 

 afterwards fecundated, as in many tirties, or that it requirts 

 only the application of artificial heat for its incubation, as in 

 Vilrds ; or that the natural heat of the climate is fuliicient, 

 as in reptiles, infeAs, &c. Thefe are flnclly evijmrous 

 animali. 



The ov'.im, after being fecundated, and detached from the 

 ovarium, remains in iome animals within the body of the mo- 

 ther, until the contained germ be developed and hatched. 

 Thefe are fii!/} viv':parou: animals, or ovo-vlviparous. The 

 viper and lome fiihes afford inftancee of this procefs. 



The mammalia alone are truly viviparous animals. Their 

 n-erm poffefies no provilion of nourifhment, but- grows by 

 what it derives from the juices of the mother. For thispur- 

 pofe it is attached to the internal furface of the uterus, and 

 fometimes by accident to other parts, by a kind of root, or 

 infinite ramification of veffels, called a placnta. It is not 

 therefore completely fepai"ated from the m.other by its cover- 

 ings : and it does not come into the world until it can en'ioy 

 an independent organic exiftence. The mammalia cannot 

 therefore be faid to poffefs an ovum, in the fenfe which we 

 have affigned to that term. 



According to this flcetch of the fubjecf, generation may 

 be faid to confift of four funftions, differing in their import- 

 ance, and in the number of animals, to which they belong, 

 ■ufa : ift. The pradud'ton of the germ, which is a conftant 

 circumilance : zdly. Fecundation, which belongs only to 

 tbofe inftances where there is a dilhnclion of iexes : 3dly. 

 Copulation, which is confined to thofe kinds of fexual gene- 

 ration in v.-hich fecundation is accomplidied within the body : 

 iaftlv, Utcro-gejlation, which belongs exclulively to viviparous 

 generation. The generative organs may be moft naturally 

 arranged according to this diftribution of the partial func- 

 tions, which thev execute. The finiple production ot a 

 germ, or gemmiparous generation, may be accomplilhed at 

 any point of the body, and has, therefore, no peculiar 

 organ. Sexual generation demands an organ for the produc- 

 tion of germs, and another for that of the fecundating liquor. 

 Modes of union are neceffary when copulation takes place : 

 and gellation requires a rect-ptacle adapted to die abode of 

 the fu;tus. Thus we have preparatory and preferving or- 

 fjans ; inftruments of copulation ; and organs of education. 

 Thofe of the two flrll clafTes are divided into male and fe- 

 male ; the lall belong to the latter fex only. The prepara- 

 tory and preferving organs of the males fccrete the femen, 

 and the other fluids which are to be mingled v.ith it, and re- 

 tain thefe fecretions. They conlift, in their moft compli- 

 cated form, I If. Of the tejlicles, which prepare the feminal 

 fluid, and conduct it, either into a particular refervoir, or 

 into a canal, from which it is conveyed out of the body, or 

 into a cloaca, from which it is in like manner ejected : zdly. 

 Of the vficuU femiralcs, luppofed to be refervoirs for the fe- 

 men : 3dly. Of xhe projiate glands ; and, 4thly. Of Caliper's 

 ylnnds, which feparate a peculiar fluid, mixed with the iemcn 

 at the time of coition. The teflicles are abfent in the lail 

 clailes only of the animal kingdom, where generation is per- 

 formed bv a fimple divifion of the animal, or by (hoots. 

 They exift in all the clalfes of vertebral animal ; and. of the 

 invcrtebral divifion, in the molhifca, cruftacea, iniedts, and 

 moft vermics- Their number, ftrufturc, &c. differ very much 

 in thefe various claffes. The vcficula;, proilatc;-, and Cow- 

 pcr's glands, being let's effeiitial in their functions, are much 

 leis generally found, and are chiefly confined to the firfl 

 claffes of the animal kingdomi. The preparatory female 

 drgans fervc the purpofc of developing and preferving the 



germs. Their exiflence is as general as that of tlie partt 

 juft mentioned ; but they are much more fimple in th.e firll 

 clafs of the animal kingdom. They confift of two bodies 

 fimilar in form, fi/.e, and ftruftuie, and named by modern 

 phyfiologifls ovaria, in order to cxprefs more accurately, than- 

 by their old name of teUcs, t!ie function to which they are 

 deftined. In faft, if their flrurture, confidcred fimply in 

 man, and moil of the mammalia, leave any doubt concerning 

 their office, its nature is fo evident in the other chiffes, that 

 their function cannot fail to be recognized. In all the claffes 

 which fuccecd the mammalia, the o\':iry or ovaries lerve evi- 

 dently for the production and prefervation of the germs or 

 ova, which are formed in thefe bodies prevloufly to the ap- 

 proaches of the male. Analogy leads us to conclude that 

 the fame circumftance holds good in the mammalia f and this 

 concluiion is one of the moft important refultsfrom the ftudy 

 of comparative anatomy and phyliology. 



The organs of copulation, in the male fex, confift of ov,'^ 

 or more projefting bodies, called penes, generally perforated 

 by a canal, named the urethra, capable of being introduced 

 into the feir.ale organs, in order to convey to them the fecim- 

 dating liquor, or for the fimple purpofe of producing an irr:- 

 tation neceffary for conception ; or they are fupemumcrary 

 members, enabling the male to grafp and hold the female. 

 In the latter fex, the copulating organs confift of canal:, 

 particularly defigned to receive the male penis, or give pai- 

 fage to the products of conception : or of cavities, wlucli 

 ferve alfo for other purpofcs, but which, at the time of copu- 

 lation, receive the penis, and tranfmit tlie fecundating liquor 

 to the educating organs. 



The educating srgans receive the germ or ovum, after its 

 detachment, from the ovarium, retain it for a greater or lefs length 

 of time,contribute in a more or lefsdirect manner to itsgrowth, 

 and convey it out of the body : or they furnifh nourifhment to 

 the young, when born, or afford it a temporary lodging. 

 They are, therefore, divided into external and internal parts.. 

 The latter may be again diftinguiibed into two kinds. 

 The firft of thefe are fimple canals, through which the germ 

 or ovum is to pafs, either in order to be conveyed out of the 

 body (as in the egg), or to be tranfmittcd into the parts of 

 the fecond defcription. The latter are vei-y dilatable bags, 

 to the pariete.s of which the germ is attached by means of 

 veffels conveying the materials of its nutrition, and preferv- 

 ing it in this way until it has acquired a certain degree ot 

 growth. Organs of the firft kind are formed in the four 

 claffes of vertebral animals ; and are called Fallopian tubes in 

 the mammalia, ov'uiuSs in the birds, reptiles, and fifhes. 

 Parts of the latter defcription belong to the mammalia only, 

 and arc the uterus. The external educating organs are, in 

 the mammalia, the mammary glands fecreting the milk by 

 which the you:-ig are nouriflK-d ; or receptacles, in whic'i 

 thev are retained for a time, in a few genera. One kind ot 

 reptiles only poffeffes analogous pouches. 



To fill up the outline which we have prefer.ted to cur 

 readers in the preceding fketch, would require a detailed de- 

 fcription of organs varying almolt infinitely in form and 

 ftruclure in the different clafles of organized bodies. Thefe 

 details vvi:l be found in the proper articlt-s of the Cyclc- 

 pxdia, relating to vegetable and comparative anatomy : this 

 gtneral viechas been thought neceffary, as introdiKtory and 

 explanatory. The remainder of this article will be devoted 

 to the anatomy and phyfiology of the generative organs in. 

 the lium.an fubjeft. The growth and developement of the 

 ovum in the uterus have been confidered under the article 

 E.Mnityo, and the anatomy of the mammary gland will be 

 found under Breast. 



The preceding account will fnew what various methods 

 are employed by nature for the perpetuation of the- races of 



B. i orga..- 



