A method is described of inducing shivering constantly in normal subjects. The relationship between the onset and cessation of shivering to rectal temperature change is discussed. Cases with manifest disease of the central nervous system were made to shiver and the responses observed. From the investigations it has been shown that shivering, as produced by the constant method described, is independent of pyramidal thalamic and cerebellar integrity, although the type of tremor produced is modified by cerebellar dysfunction. The conclusion is reached that the effective stimulus is a falling blood temperature acting directly on a “centre” or on a thermosensory mechanism capable of stimulating the shivering “centre.” The downward pathway from the “centre” is by exclusion shown to be an extrapyramidal pathway, either the tectospinal or rubrospinal.