THREE FIGURES
Herrmann and Nicholas ( '48) have described the relative concentration of the three major protein fractions of skeletal muscle in rats from mid-fetal life to 30 days of age. The three fractions (insoluble, actomyosin, and soluble) appeared to increase in concentration, but at different rates, until about the 15th day after birth. Thereafter, there occurred a progressive diminution in concentration of the insoluble fraction and a corresponding increase in the actomyosin fraction. In this latter connection, it is of interest that the late-lactation paralysis observed in the suckling young of rats low in vitamin E usually appears between the 17th and 25th days (Evans and Burr, '28; Olcott, ' 3 5 ; Pappenheimer, '39) and that institution of E-therapy after the 15th day is usually ineffective (Evans and Burr, '2s). This suggested the studies recorded here, which are concerned with these same fractions of musole of vitamin E deficient and normal rats, in the hope that deviations from thc normal protein picture, if observed, might throw some light on biochemical changes directly or indirectly related to the process of experimental muscular dystrophy.
1 These stiidies were supported by a grant-in-aid from the Mnscrtlar Dystrophy -4ssociations of America.