An analysis of physiological states responsible for antero-posterior disintegration in Planaria dorotocephala

Summary Planaria were treated with equi-molal solutions of ammonium, potassium, sodium, magnesium, and calcium chlorides, made up in distilled water and the rates of cytolysis compared with cytolysis in distilled water. Potassium and ammonium accelerate cytolysis; some protection is afforded by sodium; still more by magnesium, and complete protection by calcium in the concentrations employed.In distilled water solutions of calcium chloride no cytolysis occurs in concentrations from M/500 to M/40,000; cytolysis is distinctly delayed in M/100,000. The protective action of M/1,000,000 is detectable.Potassium oxalate accelerates disintegration in hypotonic solutions.One per cent ethyl alcohol in distilled water causes cytolysis more rapidly than does distilled water alone, but in M/500 molal calcium chloride the alcohol solution is much less effective.Ringer's solution minus calcium affords no protection against death due to absence of calcium and death due to potassium oxalate but completely protects against cytolysis. Death in Ringer's solution minus calcium and in Ringer's solution with potassium oxalate occurs first in the anterior region and describes an antero-posterior gradient.Cytolysis in distilled water, in potassium oxalate solutions, in alcohol solutions, and in hypotonic calcium solutions of extreme dilution is initiated in the anterior end and describes an antero-posterior gradient within a zooid.Earlier work of the writer on the disintegrative action of lipoid solvents, heat, KNC, hyper- and hypotonic solutions is discussed. It is concluded that inPlanaria dorotocephala the antero-posterior gradient in cytolytic disintegration represents an antero-posterior differential in sensitivity to disturbance of the calcium-lipoid-water relation in the organism.