Caspersson, Hyden and Hartelius, in a series of researches at the Caroline Institute, Stockholm, found that (a) nerve cells subjected to heavy stimulation become depleted of nucleoprotein; (b) nitrile compounds administered to the experimental animal hasten regeneration of this nucleoprotein; (c) biopsy specimens of the prefrontal cortex of psychotics removed at leucotomy show a reduction of cellular protein when compared with healthy subjects killed in accidents; (d) nitrile compounds have a beneficial stimulating action in psychotics and sometimes a permanent curative effect. The substance which they used, malononitrile, was toxic, liable to produce severe reactions and only usable with safety if, after the injection, the patient was kept under observation and given sodium thiosulphate at the first sign of trouble. Meyer and Meyer (1949) have adversely criticized their methods and conclusions.