The Cellular Basis 



147 



owing probably to the peculiarities of the cytoplasm of these cells. 

 These nuclear differentiations are caused by differential divisions 

 of the cytoplasm and not of the nucleus. But while the chromo- 



FIG. 48. GASTRULA AND LARVA OF Styela, showing the cell lineage of vari- 

 ous 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. 



