ON THE MAMMALIAN NERVOUS SYSTEM. 343 



it is impossible to tabulate the facts in the definite manner used for the historical 

 retrospect of the graphic and other methods. 



Moreover, since the interpretation of the results is completely dependent upon the 

 methods of experiment in each case, it will be better to arrange the facts as follows : 



(1.) Excitation experiments on the cortex. 



(2.) Excitation experiments combined with division of commissures, i.e., corpus 

 callosum, &c. 



(3.) Excitation experiments combined with the excision of the opposite " motor " 

 area. 



(4.) Excitation experiments combined with hemisection of the spinal cord or bulb. 



(5.) Ablation of one hemisphere. 



(G.) Ablation of the "motor" area of one hemisphere followed by ablation of that 

 of the opposite side. 



(7.) Excitation of the corpus callosum. 



(8.) Degeneration of fibres after excision of portions of the cortex cerebri. 



We will now briefly state the more important facts determined by the above 

 methods of experiment, postponing for the present any criticism. 



1. Excitation Experiments on the Cortex. 



It was first observed by HITZIG,* later by FERRIER,! ALBERTONI,^ and MUNK, and 

 subsequently by FRANCK and PITRES,|| that powerful excitation of one hemisphere in 

 the Carnivora produced movement not only of the corresponding or opposite side of 

 the body, but also of the same side as that stimulated. 



FRANCK and PITRES|| showed further that when the muscles of the same side were 

 thrown into action they contracted '01 second later than those of the opposite side, a 

 most important observation. 



BUBNOFF and HEIDENHAIN,! CARVILLE and DuRET,ir confirmed these facts. 



JANICKE"** observed that while in dogs bilateral representation of the facial muscles 

 was very constant, in the limbs on the contrary, unilaterality was the rule, but that 

 to this there were exceptions. His views were confirmed by UNVERRICHT. 



LEWASCHEwtt noted that the movement on the opposite or corresponding side was 

 a coordinated one (like a voluntary action), whereas that of the same side, besides 

 being late, was only a simple tonus. 



* ' TJntersuchungen uber das Gehirn,' Berlin, 1874, pp. 48, 134. 



j- ' Functions of the Brain,' 1st ed., 1874. 



% ' Lo Sperimentale,' 1876. 



' Gesammelte Abhandlungen,' 1890. 



|| ' Compt. Eend. Laboratoire,' MAEET, 1878, 1879. 



^f Loc. eit. 



** ' Centralblatt fur klinische Medicin,' March, 1883, p. 177. 



ft Loc. cit. See p. 346, infra. 



