Symptoms and causation of the planarian disease related to cancer.
The disease provoked by injections of water and other harmless liquids or wounds without tissue loss, is characterized by the regression of certain organs, opening in the epidermis, pigmentary anomalies and malignant tumors. The very few worms which recover spontaneously, regenerate the eliminated parts or develop supernumerary structures. Wound are producing the disease less frequently when planarians are undernourished. The disease can also manifest itself spontaneously, especially in the summer. Diseased worms become unable to regenerate. During a transitory period epimorphosis is still possible but is not followed by morphallaxis. The symptoms of the disease manifest themselves in the regenerated parts. A fragment cut out from a worm that just became diseased regenerates and recovers completely. The results give additional evidence to the earlier conclusions about the "type I cell" system of planarians. The disease is provoked by an excessive activity of this system with respect to the animal's actual need and is analogous both to cancer and the consequences of X-ray treatment.
D002455:Cell Division; D006801:Humans; D008954:Models, Biological; D009369:Neoplasms; D012038:Regeneration; D014419:Turbellaria / Q000502:physiology*