The Cellular Basis 



147 



may not do so. Nuclear achromatin and oxychromatin, like the 

 cytoplasm, may divide unequally and differentially, and this is 

 probably a prime factor in development. 



FJG 48. GASTRULA AND LARVA OF Stycla, showing the cell lineage of var- 

 ious organs, and the distribution of the different kinds of protoplasm to 

 these organs. Muscle cells are shaded by vertical lines, mesenchyme by 

 horizontal lines, nervous system and chorda by stipples. 



