WALDENSTRÖM1 has divided the porphyrias into the following groups: Porphyria congenita, a familial disease, probably recessive in character, present at birth and characterized by sensitivity to light, pigmented bones and teeth, and greatly increased coproporphyrin and uroporphyrin excretion, mainly of Series I. Porphyria cutanea tarda, a disease in which the porphyrinuria and sensitivity to light develop later in life and a sclerodermic tendency is noticeable. The occurrence of colic and the occasional excretion in the urine of uroporphyrin suggest a relationship with the group next to be described. Severe nervous symptoms have not yet been reported.2 Porphyria acuta, a familial disease, dominant in character, accompanied with the excretion of coproporphyrin and uroporphyrin mainly of Series III. The following clinical forms have been recognized: (a) Latent porphyria in which there is increased uroporphyrin excretion without any clinical manifestations of porphyria; such patients as have been encountered have always been