Experimenal catatonia was described originally by H. de Jong and H. Baruk (1) as occurring in different animals following the injection of certain doses of bulbocapnine. Later (2) it was found that this syndrome may be elicited by many other physical and chemical methods. Experimental catatonia is, therefore, a general reaction-form of the central nervous system. It may be subdivided into: (A) Hypokinetic and (B) Hyperkinetic forms.(A) HYPOKINETIC SYMPTOMS(1) Diminished motor initiative, i.e., the impulse to movements and acts is diminished. This may occur to such a degree that the animal remains motionless in a drooping position, always remaining in one spot for many hours.(2) Catalepsy. This is a variety of diminished motor initiative. The animal assumes positions passively introduced by the examiner. Catalepsy is not only limited to the extremities but is found in the whole body.(3) Negativism, a physiological phenomenon consisting of passive and active resistance to changes of positions already assumed.