Microenvironmcntal Influences in CytodiiTerentiation 231 



FILTER-CELLOPHANE ASSEMBLY 



12 



CELLOPHANE 

 FILTER 



MESENCHYME 

 XLOT 





CLOT- 



MEDIUM 



SUPPORTING ROD 



PLEXIGLAS RING 





«• s 



SPINAL CORD 







PLATE VI. FIG. 12. Diagram of cellophane with small hole interposed between 

 inductive interactants. FIG. 13. Fixed and stained whole mount. Note edge of hole 

 in cellophane marked by arrows, epithelial rudiments forming. 



