MINOT, Frank, and Dziewiatkowski1 in 1949 reported on the discovery of pentose- and phosphorus-containing complexes in the urine of patients with progressive muscular dystrophy. They found that when 8 to 10 drops of urine from a patient with a disorder of this type was heated in a boiling water bath for 45 minutes with 5 cc. of Benedict's qualitative solution, reduction was invariably obtained. The substance responsible for this reduction was identified as d-ribose, which is excreted as a phosphorus-containing complex. Orr and Minot2 suggested that this observation could be made the basis of a diagnostic test for muscular dystrophy. They examined specimens of urine from 26 cases of progressive muscular dystrophy of all types, from 6 of dystrophia myotonica, from 5 of myotonia congenita, and from 3 of amyotonia congenita and discovered ribose in all of them. On the other hand, a negative result was obtained