1885.] Experimental Researches in Cerebral Physiology. 405 



Methods. — Our method of proceeding has been to excite these 

 several parts in succession, and record the contractions of one of the 

 limb muscles upon a moving blackened surface, either by directly 

 connecting the tendon with the lever of a myograph, or by Marey's 

 method of transmission by tambours and indiarubber tubing, the time 

 being simultaneously recorded upon the moving surface by a clock 

 marking seconds. Usually the rate and duration of the excitation 

 were also recorded by a small electromagnet. Besides the contrac- 

 tions resulting from electrical excitation, we have frequently obtained 

 an accidental record upon the moving surface of spontaneous or 

 voluntary contractions of the muscle the responses of which to elec- 

 trical excitation of the cortex cerebri we were preparing to record, 

 and we have thus been able to compare these records of voluntary 

 contractions in animals both with the results of electrical excitation 

 of the several parts of the motor tract in the same animals, and with 

 records of voluntary contractions in the human subject. We have 

 also studied in the same way the epileptoid contractions which are 

 often found to follow a period of electrical excitation of the cortex 

 cerebri in animals, and have compared these epileptoid contractions 

 with numerous others recorded by one of us from cases of true epi- 

 lepsy and other affections of the nervous system (in ihan and animals) 

 accompanied by rhythmic muscular movements. 



Results. — It was somewhat vaguely stated by Franck and Pitres,* 

 and has generally been admitted by other authors, that so far as 

 regards the rhythm of muscular response, the result of exciting either 

 the cerebral cortex or any other part of the motor tract is precisely 

 the same as that which is well known to be the case with the excita- 

 tion of the motor nerve, namely, that for all rates of excitation the 

 rhythm of muscular response is identical with the rhythm of excita- 

 tion. Our experiments on the contrary show that this statement only 

 holds good for low rates of excitation up to about ten or twelve per 

 second, but that for all higher rates of excitation of the cortex 

 cerebri, corona radiata, or medulla spinalis the muscular response does 

 not vary with the rate of excitation, but maintains a constant rhythm 

 which is independent of the excitation rate and approximates to ten 

 per second. 



The muscle-curves which we have obtained from different mammals 

 as the result of successive excitation of the cortex cerebri, corona 

 radiata after removal of the superjacent cortex, and of the cervical 

 cord after section below the medulla oblongata, are very similar to one 

 another, and exhibit along their course, both at the commencement 

 and during the whole extent of contraction of the muscle, small but 

 distinct undulations following one another at the rate of about ten 



* " TraTaux du Laboratoive cle Marey," iv, 1879, pp. 412-447. See also a paper 

 by the same author in the " Arch, de Physiologie," Nos. 1 and 2, 1885. 



