446 OF GENERATION AND DEVELOPMENT. 



more commonly developed in certain distinct portions of the fabric; 

 being sometimes formed in the midst of solid masses of areolar or cel- 

 lular texture ; whilst in other instances they are developed, like the 

 spermatic cells, in the interior of tubes and vesicles resembling those 

 of glands, and furnished with an excretory duct. The latter condition 

 obtains in the greater proportion of the higher Invertebrated animals, 

 and in some Fishes ; but in the Vertebrated classes we return to the 

 type which characterizes the egg-producing organs in many Zoophytes, 

 namely, the development of the egg in the midst of a mass of solid 

 parenchyma, from which it gradually makes its way, to escape into the 

 visceral cavity. The Ovarium of the Mammal, Bird, or Reptile, as well 

 as that of most Fishes, differs entirely, therefore, from that of the In- 

 vertebrata; for the latter have all the essential characters of true 

 glands ; whilst the former are nothing else than masses of parenchyma, 

 copiously supplied with blood-vessels, and having dispersed through 

 their substance certain peculiar cells, termed ovisacs, within which the 

 ova are developed. In order that the latter may be set free, not only 

 must the ovisac itself burst (like parent-cells in general), but the pecu- 

 liar tissue and the envelopes of the ovarium must likewise give way. 

 When the ova thus escape into the abdominal cavity, they may lie there 

 for some time, at last to be discharged through simple openings in its 

 walls, as happens in those Fishes which have this form of ovarium ; or 

 they may be at once received into the trumpet-shaped expansion of 

 tubes, that shall convey them to these orifices. These tubes are termed 

 oviducts, in common with the excretory ducts of the glandular ovaria 

 of Invertebrated animals ; for their function is the same, that of con- 

 veying the ova to the outlet by which they are extruded from the body. 



Fig. 137. 



The Uterus with its appendages viewed on their anterior aspect. 1. The hody of the uterus. 2. Its fundus. 

 3. Its cervix. 4. The os uteri. 5. The vagina; the number is placed on the posterior raphe or columns, 

 from which the transverse rugas are seen passing off at each side. 6, 6. The broad ligament of the uterus. 

 7. A convexity of the broad ligament formed by the ovary. 8, 8. The round ligaments of the uterus. 9, 9. 

 The Fallopian tubes. 10, 10. The fimbriated extremities of the Fallopian tubes; on the left side the mouth 

 of the tube is turned forwards in order to show its ostium abdominale. 11. The ovary. 12. The utero-ova- 

 rian ligament. 13. The Fallopio-ovarian ligament, upon which some small fimbriae are continued for a short 

 distance. 14. The peritoneum of the anterior surface of the uterus. This membrane is removed on the left 

 side, but on the right is continuous with the anterior layer of the broad ligament. 



They are represented in Mammalia by the Fallopian tubes, which are 

 true oviducts, although they terminate in the uterus instead of proceed- 

 ing directly to the outlet. And it is by the fimbriated extremities of 

 the Fallopian tubes (Fig. 137, 10, 10), which apply themselves closely 



