The Farm-poultry . e subject of biology. It is important that these facts should beconsidered at the outset; for such is the arro-gance of science, such her evasion of questionswhii-h she is unable to answer, and such herassumption of authority that the reader is iu in the development of the brain, spinal cord,nerves, ej e~. epidermis, scales, nail-, feathers,ami the mucous membranes of the mouth,throat and nose. The inner layer, or hypo-blast, gives rise to the epithelium lining theintestines. From the outer layer of the myo-blast are developed the muscles of the trunk,and the bony framework
The Farm-poultry . e subject of biology. It is important that these facts should beconsidered at the outset; for such is the arro-gance of science, such her evasion of questionswhii-h she is unable to answer, and such herassumption of authority that the reader is iu in the development of the brain, spinal cord,nerves, ej e~. epidermis, scales, nail-, feathers,ami the mucous membranes of the mouth,throat and nose. The inner layer, or hypo-blast, gives rise to the epithelium lining theintestines. From the outer layer of the myo-blast are developed the muscles of the trunk,and the bony framework of the body. Fromthe inner stratum the various internal organs,the blood and the blood vessels. While the development of these membranesis in progress there appears at the originalseat of the genu a tiny transparent furrowcalled the primitive trace. Shortly after itsformation ridges begin growing along itsmargins. These, increasing in height andbending inward, unite to form a closed tube,the neural canal. Fig. 85s1. Diagrams to show the development of the three layers of the blastodermic (vesicle or) membrane in transversesections: — A. portion ot the ovum with the zona pellnclda and the germinal an a. B. (. I), K, K. (i. differentstages of development; o, umbilical vesicle: a. amnion: 1, Intestine: p, peritoneal cavity, bounded by thesphmchno-plciiral and snmato-plcural layers of me-,.blast; 1 vitelline membrane: 2, external blastodermiclayer (epiblast); .), middle layer (mesoblast); 4. internal layer (hypoblast): 5. medullary lamina and groove;.V, medullary canal: G, epidermic lamina: 7, lateral flexures of the amnion: 7, the same almost iu contain : K,Internal epithelial layer of the amnion; 9. epidermis of the embryo; lb, chorda dorsalis; 11,vertebral lamina*:1.\ protoveriebi:e proper; 1:1, muscular laminae; 14, lateral lamina: 15, tlbro-lntestlnal lamina: 16,cutaneouslamina*; 17. Internal fibrous layer of the umbilical vesicle; 18, muscular lamina* extending to meet the
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectpoultry, bookyear1901
