THE CAT
I n a paper 011 estciisor t o m s after spinal-cord lesions in the cat, Xmsoii, hIuir, and Xeiss ( ' 3 2 ) presented evidence that the pyramidal tract exerted an inhibitor>-influence 011 the spinal mechanism for extensor tonus. Tt is generally admitted that pyramidal lcsions in nian c*aiise stiffness as well as paralysis of the limbs. Howe-er, experiments 011 cath have for the most part failed to give clear evidence of this function of the pyramitlal tracts in thew animals. Warner and Olmsted ( ' X I ) , Olmstecl and Logan ( ' 2 5 ) , King ( ' 2 7 ) , and Laiigwortliy ( 2 8 ) found that removal of the motor cortex in cats did not came extensor rigidity. This dewloped only wheii the cortex of the frontal area rostra1 to the motor cortcx was removed. On the other hand, Langhton ('28) and McI<ibhen ('29) state that removal of the motor cortex was in itself sufficient to produce a state of hypertonus in the extensor muscles of the contralateral limbs. The motor and premotor portioiis of the cortex a r e so closely related topographically that wheii one is removed there is a possibility that the other may be i i i j ~r c d also-and some such con- sideration as this may account for the conflicting iiatnre of thc results just mentioned.
Langworthp ( '28) approached the problcm in another waS. He severed the pyramidal tract$ a t their decnssation by i1 medial sagittal section of the medulla oblongata. In ordcr to be sure that tlirse tracts were completely cut. R long iucihion was made ~vliieh mow or less serionsly damaged the median lemiiisciis and the arciia te and olivary fibers. Th