The essential thing here was the following. Whether the disease develops or not, whether it is manifested in one form or another, depends on the type of the given animal’s nervous system. The neuroses were manifested in a weakening of both processes separately or together, in chaotic nervous activity, and in different phases of the hypnotic state. Various combinations of these symptoms represented very definite pictures of diseases. Under usual conditions the disease was observed after castration in animals of the central type only for a period of a month; subsequently the animal behaved normally. Only during increased excitability was it possible to establish a constantly diminishing efficiency of the cortical cells, whereas in cases of conditioned food reflexes it was easy to modify the excitability by different degrees of hunger.