Consensual or associate muscular action consists in the contraction of a single muscle of a particular set being followed by a determinate movement of the others, independent of, and oftentimes contrary to the will : one eye, for instance, cannot be changed in its axis without being followed in the same direction by the other. The following experiments illustrate this mode of action. The first movement of the series is perforce produced, and the associate movements follow in consequence. "In a pigeon," M. Flourens "removed both cerebral hemispheres; loss of vision immediately ensued, with general loss of power, which, however, was neither considerable nor persistent. The pigeon flew when it was thrown into the air; walked when it was pushed. The iris had its power of motion in both eyes.; the animal was deaf, and it did not move spontaneously, but had constantly the manner of a sleeping animal, and, when irritated, it resembled in its motions an animal just awaking. In whatever position it was placed, it resumed its equilibrium; if laid upon the back, it got upon its feet again ; Water being put into its beak, it swallowed it; and it resisted attempts to open its beak." "He likens the pigeon in this condition to an animal condemned to perpetual sleep, but without the faculty of dreaming."* "M. Hertwig removed the upper part of the hemispheres in a pigeon; sight and hearing were abolished, and the animal sat in one spot as if asleep. He fed it: peas, if placed merely within the beak, were not swallowed; but if laid upon the tongue, they were (owing to reflex action); the muscles were but slightly enfeebled; the bird stood firmly, and flew when thrown into the air. This state endured for a fortnight, when the hearing and sensibility in a great measure returned; this pigeon lived three months." "A hen, in which he had cut off both hemispheres nearly to the base of the brain, was found to be deprived of sight, hearing, taste, and smell; it sat constantly in one spot, and was as if dead until strongly roused, when it moved a few steps. The animal lived in this state of stupor, without its senses being restored, for three months."*

* Muller's Physiology. 2*