82 ?.-0>.TF.OfeE T. BI-RROWS 



CONCLUSIONS 



1. The tissues of the embryo chick can be cultivated outside 

 the body in a medium of plasma, prepared from blood of adult 

 chickens. 



2. Nerve fibres grow from the embryonic neural tube which 

 has been cultivated in blood plasma. These fibres react to specific 

 nerve stains and have the histological characters of normal 

 embryonic nerves. 



3. The growing nerves can be readily observed in these cul- 

 tures. They grow by an independent activity of their own pro- 

 toplasm. 



4. The growth of the mesenchyme tissue consists in the wan- 

 dering out of the preexisting tissue cells and their multiplication 

 by mitotic division. 



5. The morphology and the arrangement of the mesenchyme 

 cells are dependent on the physical characteristics of the plasma 

 clot. 



6. Muscle cells appear as chains of striated cells from the bor- 

 der of the heart and the myotomes. 



7. The embrj^onic heart transplanted to this culture medium 

 beats for several days, often with a normal rhythm and force. 



8. This method of growing tissues in culture permits only of 

 the histogenetic study of the cells and the nerve fibres. Struc- 

 tures comparable to organ formations of the body are never ob- 

 served . 



