“…During the early years of the present century a controversy arose as to the identity of the cystine from proteins with that from urinary calculi. Neuberg and Meyer (34) detailed a large number of points of difference between cystine from the two sources and Morner's work (30,31,32), in which he obtained -thiolactic acid from cystine, served to strengthen the view that stone cystine was the disulfide of a-thio-0-aminopropionic acid. Fischer and Suzuki (15), however, showed that Neuberg and Meyer's points of difference were all due to the presence of tyrosine in their preparation of stone cystine, and Gabriel's synthesis (18) of a-thio-|S-aminopropionic acid, which differed in many ways from cysteine, finally settled the matter.…”