THE GROWTH OF TISSUES OF THE CHICK EMBRYO 

 OUTSIDE THE ANIMAL BODY, WITH SPECIAL 

 REFERENCE TO THE NERVOUS SYSTEM 



MONTROSE T. BURROWS 



AssistaM, Rockefeller Institute for Medical Research, New York 

 From the Sheffield Biologiccd Lahoratory, Yale University 



FOURTEEN FIGURES 

 FIVE PLATES 



The relation of fibrin to the healing of wounds in the animal 

 body, to the formation of adhesions in serous cavities has long 

 been known to pathologists. Clots of blood and serous fluid oc- 

 curring in various forms of injury, act, according to our present 

 knowledge of the subject, as a supporting framework on which 

 connective tissue, blood vessels and the epithelium grow to bring 

 about the healing of a wound. 



The use of fibrin clots outside the body as a culture medium 

 for growing embyronic tissue, we owe to Harrison ('07-' 10). 

 This author has conclusively proved, by means of a long series 

 of experiments, that embyronic tissue of the frog will undergo 

 development of a normal type for a considerable period of time, 

 when transplanted into a coagulable lymph. The isolated central 

 nervous system of a frog-embryo, removed to a cover slip at a 

 period of development just prior to the appearance of peripheral 

 nerves and covered with fluid lymph from the lymph sac of an 

 adult frog, is firmly held by the coagulating lymph and passes 

 through a period of considerable development, growing long nerve 

 fibres. These fibres, as this author has described, grow in the 

 meshes of the fibrin by an independent activity of their own 



