315fect, this action of morphine upon the gut must be mediated through the central nervous system. Similar actions have also been observed in rats and guinea pigs. 2. Pharmacological inhibition or blockade of this morphine action upon the gut could not be demonstrated with a wide variety of autonomic blocking agents or central nervous system depressants. Concurrent, surgical interruption of the sympathetic and parasympathetic outflows from the central nervous system to the gastrointestinal tract also failed to block the activity. 3. The findings suggest that morphine may be causing inhibition of gut propulsive action by initiating a neurohumoral discharge from the central nervous system into all the circulating blood of the body. I am indebted to J. Pollock, M. Shaw, E. Eckhardt and M. T. Spoerlein for technical assistance. 1. Hrueger, H., Physiol. Rev., 193'1, vl'1, 618. 2. Hrueger, H., Eddy, N. B., Sumwalt, M.,

A significant inhibition of mitotic activity in the epithelial cells in the crypts of Lieberkuhnl in dba mice was produced by repeated subcutaneous injections of an aqueous alcohdtreated extract of beef spleen.( 1) In the present experiments the effect of a single subcutaneous injection of splenic pulp of homologous and heterologous origin on mitotic activity of the cells in the crypts of Lieberkiihn has been investigated in a highly inbred and a heterozygous strain of mice.Experimental. Twelve dba line 1 mice from the Jackson Memorial Laboratories and 9 of the Rockland Farm all-purpose strain were employed in this study. The mice were approxim,ately 6 to 8 weeks old and were allowed fo'od and water ad libitum. Spleens were removed aseptically from donor mice of the same strains, pulped by passage through a fine meshed wire screen, and diluted 1: 1 with Ringer's solution. A single subcutaneous injection of 0.5 cc was made into the groin of each experimental animal, and 7 days later the animals were killed, always at the same hour of the day in order to avoid introducing the diurnal variable in the mitotic cycle.(2) -4t autopsy a short segment of the small intestine located 20 mm distal to the pylorus was removed, fixed in Bouinl's solution, dehydrated and embedded in paraffin. Histologic sections 8 mu in thickness were stained with hematoxylin.Mitotic figures including those from late prophase to late anaphase were counted in the epithelium of the crypts olf Lieberkuhn in cross sections of the gut. Ten sections from progressive levels of tfhe segment sufficiently separated to rule out counting the same figure more than once were used from N., Can.