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		Procedure I. Animals: Strongylocentrotus purpuratus or Lytechinus pictus, from the Pacific coast, or Lytechinus variegatus, from the Atlantic Coast and Gulf of Mexico can be used for this experiment. S. purpuratus and L. pictus gametes and embryos must be kept close to 13- 15ºC, or they will not develop. Gamete collection by induced spawning 1. Induce spawing of gametes and fertilize as described in the basic protocols. 2. Collect both sperm and eggs. II. Treatment with LiCl Solutions and Examination: 1. Use a 60 mM solution of LiCl2 in ASW to prepare 30 mM and 15 mM solutions. 2. At the two-cell stage, transfer embryos from ASW to seawater with each of the three LiCl2 concentrations. A quarter of the embryos should remain in ASW as a control group. 3. At the mesenchyme blastula stage, transfer 50 ml of embryos in finger bowl to ASW. 4. Observe samples of embryos from a control (ASW with no lithium added) culture and each of the experimental cultures the next day. 5. Use 2-3 drops eggs/embryos on a depression slide to compare developmental rate and morphology of the groups; focus on vegetal area morphology of embryos.