6 CONTENTS ERRATUM VOL. 52, 1955. Page 388, line 24. The clause and is in keeping . . . . . . crude ratio 2 : 1 : 1 should be transposed to follow like tyrosine on line 22.6 CONTENTSERRATUMVOL. 52, 1955.Page 388, line 24. The clause and is in keeping . . . . . . crude ratio 2 : 1 : 1 shouldbe transposed to follow like tyrosine on line 22