That the loss of will power is gradual was proved by decapitating _Polistes pallipes_. A day after the operation she was standing on her legs and opening and closing her wings; 41 hours after the operation she was still alive, moving her legs, and thrusting out her sting when irritated. _Ichneumon otiosus_, after the removal of its head, remained very lively, and cleaned its wings and legs, the power of coördination in its wings and legs remaining. A horse-fly, a day after decapitation, was lively and flew about in a natural manner.[44] When the abdomen is cut off, respiration in that region is not at first interrupted. The seat of respiratory movements was referred by Faivre to the hinder thoracic ganglion, but Plateau says that this view must be entirely abandoned, remarking: “All carefully performed experiments on the nervous system of Arthropoda have shown that each ganglion of the ventral chain is a motor centre, and in insects a respiratory centre, for the somite to which it belongs” (Miall and Denny’s The Cockroach, p. 164). The last pair of abdominal ganglia serve as the nervous centre of the nerves sent to the genital organs. The recurrent or stomatogastric nerve, which, through the medium of the frontal ganglion, regulates digestion, has only a slight degree of sensibility; the insect remains quiet even when a powerful allurement is presented to the digestive tract (Kolbe). Faivre states that the destruction of the frontal ganglion, or a section of the commissures connecting it with the brain, puts an end to swallowing movements; on the other hand, stimulation results in energetic movements of this nature. Yersin, by cutting through the commissure in different places, and thus isolating the ganglia of the nervous cord of _Gryllus campestris_, arrived at the following results:— 1. The section of a nerve near its origin rendered the organ supplied by this nerve incapable of performing its functions. 2. If the connectives between two ganglia, _i.e._ the second and third thoracic ganglia, are cut through, the fore as well as hinder parts of the body retain their power of motion and sensation; but a stimulus applied to the anterior part of the body does not pass to the hinder portion. 3. Insects with an incomplete metamorphosis after section of the connectives are not in every case unable to moult and to farther develop. 4. If only one of the two connectives be cut through, the appendages of the side cut through which take their origin between the place injured and the hinder end of the body, often lose sensation and freedom of motion, or the power of coördination of movements becomes irregular. Sometimes this is shown by an unsteadiness in the gait, so that the insect walks around in a circle; after a while these irregularities cease, and the movements of the limbs on the injured side are only slightly restrained. By a section of both connectives in any one place the power of coördination of movements is not injured.