92 



GENERAL ANATOMY. 



Fig. 53. 

 A 



Diagrnms to show the development of the three layers of the blastodermic membrane on transverse sec- 

 tions. A. Portion of the ovutn with the zona pellucida and the germinal area. B C D E F G. Different 

 stages of development, o. Umbilical vesicle, a. Amnion. i. Intestine, p. Peritoneal cavity. 1. Vitelline 

 membrane. 2. External blastodermic layer. 3. Middle layer. 4. Internal layer. 5. Medullary laminae 

 and groove. 5'. Medullary canal. 6. Epidermic laminae. 7. Lateral flexures of the amnion. 7'. The 

 same almost in contact. 8. Internal epithelial layer of the amnion. 9. Epidermis of the embryo. 10. 

 Chorda dorsalis. 11. Vertebral laminae. 12. Protovertebrae proper. 13. Muscular laminae. 14. Lateral 

 laminae. 15. Fibro-intestinal laminae. 16. Cutaneous lamina. 17. Internal fibrous layer of the umbilical 

 vesicle. 18. Muscular laminae extending to meet the cutaneous. 19. External layer *f the cutaneous 

 laminae. 20. Internal layer of the same. 21. Mesentery. 22. Fibrous layer of the intestine. 



1 The dotted lines indicate the parts belonging to the internal blastodermic layer ; the plain 

 lines those belonging to the middle ; the interrupted lines those belonging to the external. 



