1905.] Effects of Alkalies, etc., on Eggs of Echinus. 129 



Fig. 19. — Undivided egg in sea-water, Fig. 20. — Undivided egg in sea-water, 

 + 0"0025 M. di-sodium phosphate, + 0"001 M. potassium hydrate, showing 

 showing two dividing nuclei. several multipolar mitoses. 



Fig. 21. — Cell in blastula in sea- water, +0 - 001 M. potassium hydrate, 

 showing multipolar mitosis. 



Fig. 22. — Cell in morula in sea-water, + 0-001 M. potassium hydrate, showing 

 asymmetrical mitosis — unequal number of chromosomes. 



