THE EFFECTS OF THIOUREA AND SOME RELATED COMPOUNDS ON REGENERATION IN PLANARIANS

¹ Department of Biology, The Catholic University of America, Washington, D. C.

1. A study was made of the effects of the three goitrogens, thiourea, phenylthiourea, and thiouracil, on Dugesia tigrina, a species of planarian. Observations were made of the effects of the drugs on healing, head formation, proboscis development, eye and skin pigmentation, and regenerative growth rate.

2. Phenylthiourea was found to be most effective in preventing healing. Both thiourea and thiouracil retarded the rate of healing.

3. Higher concentrations of all three goitrogens were effective in retarding or suppressing the normal development of sense lobes and proboscis. Phenylthiourea was most potent. Lower concentrations were ineffective. The effect was reversible.

4. Phenylthiourea inhibited eye-pigment formation, but not eye formation. The effect was reversible. Thiouracil had little effect on the formation of eye-pigment. The effect of thiourea was varied.

5. Bodies with severed tails, placed in water, showed a characteristic growth curve when body length was plotted against time in days. Plotted curves of planarians in goitrogens, compared with controls, showed retardation of growth. Noticeable recovery was made upon the return of the experimentals to water.