268 FRANZ SCHRADER. 



PLATE I. 



1. Cells in nervous tissue of the female. 



2. Cells in nervous tissue of the male. 



3 and 4. Metaphase plates from nerve tissue of the male. 



5. Spermatogonial plates. 



6. Oogonial cell. 



7. Tetrads prior to polar body formation in the egg. 

 8 to 12. Growth stages prior to first division. 



13. Metaphase plate of first division. 



