On the Reciprocal Innervation of Antagonistic Muscles. 179 



By what path such stimulation affects the motor nuclei we do not 

 know, but lesions of this region give rise to a limited degeneration in 

 the pallial tract. 



A second situated on the lateral aspect of the surface of the brain, 

 at a point corresponding to the junction of the great striate and 

 occipital tracts. 



Stimulation of this area gives rise to complicated movements, which 

 consist chiefly of deglutition, often accompanied by actual pecking and 

 by a rotation of head and neck. 



No other motor symptoms were noticed on carefully stimulating the 

 surface of the brain. Nor is any motor defect observed after removal 

 of one hemisphere. After removal of both hemispheres, a condition 

 follows which has been carefully studied by Schrader, and with the 

 description of this author we fully agree. The symptoms vary accord- 

 ing to the time which has elapsed since the operation. In the early 

 stage the animal is markedly inert, stands with flexed head, ruffled 

 feathers, and eyes shut ; the lack of initiative is pronounced. In the 

 later stage it constantly walks about, and is in a condition of continual 

 unrest, yet always avoids obstacles, and can maintain its equilibrium in 

 various positions. 



The relative importance of the mesencephalic spinal system of fibres 

 led us to examine the animals after injury of the optic vesicles for 

 indications of motor defect. 



Contrary to what has been noticed in higher animals, we are of 

 opinion that whilst a slight lesion is not followed by any observable 

 motor defect, more pronounced injury gives rise to a weakness on the 

 opposite side, so that the animal falls to that side. If the lesion be 

 very severe, the animal is quite unable to stand, and lies continually on 

 its back. 



"On the Eeciprocal Innervation of Antagonistic Muscles. Fifth 

 Note." By C. S. SHERRINGTON, M.A., M.D., F.K.S. Eeceived 

 November 29, Read December 15, 1898. 



In a previous communication upon this subject, I gave* the results 

 obtained in an experimental examination of the antagonistic correlation 

 which at least potentially exists in the muscular action of the opening 

 of the palpebral aperture. The orbicularis palpebrarum and the levator 

 palpebrce superioris are to a certain extent an antagonistic couple. 

 During the course of last year I took opportunity to examine the 

 co-ordination of the same antagonistic muscles in the movement, not of 



* ' Journal of Physiology,' vol. 17, p. 27, 1894. 

 VOL. LXIV. P 



