262 LOCALIZED ELECTRIZATION. 



paiuful, although infrequent. These slow intermissions with 

 vibration are highly useful when it is desired to act at once upon 

 the contractility and tlie sensibility or the nutrition of muscles, 

 and when a current with rapid intermissions cannot be borne by 

 the patient. For example, when rapid intermissions produce 

 cramps, and therefore cannot be used, I replace them by slow 

 intermissions with vibration, which, without being attended by 

 inconvenience, act with sufficient power upon sensibility and 

 nutrition. 



The slow intermissions with vibration are contra-indicated 

 whenever it is dangerous to over-excite sensibility. Hence the 

 aj^paratus that is provided with a trembler for producing them 

 should have also a rheotorae to give slow intermissions without 

 vibration. 



M. F. P. Le Roux, professor agrege of physical science, has 

 shown, in an excellent thesis, the importance, in certain conditions, 

 of the study of the differences between tremblers Avith and without 

 vibrations. It will be seen that the electro-physiological pheno- 

 mena produced by tremblers, and that I have stated above, are in 

 accord with his experience. 



" The necessity," he says, " to determine in an absolute manner 

 the number of interruptions has been well stated by M. Duchenne, 

 who has been careful to furnish his volta-faradic apparatus with 

 a trembler, the beats of which can be slackened or accelerated at 

 pleasure, so that it will give no more than four intermissions in a 

 second, or will produce a very great number in the same time, 

 aflfordiug also all intermediate degrees of rapidity. 



" M. Duchenne makes a distinction between tremblers with and 

 without vibrations. The tremblers with vibrations are those which, 

 between each intermission are agitated by several rapid recoils or 

 rebounds, which render electrization very disagreeable. Save in 

 certain cases, one should avoid the arrangements of a trembler 

 which produce these effects, because they render certain electro- 

 muscular experiments more difficult. 



"We know that very closely approximated electric shocks 

 produce a tetanic condition instead of isolated contractions ; the 

 vibrations in the trembler produce in reality a series of tetanic 

 convulsions of more or less duration and separation. 



" The facts of a purely physical kind that I have observed 

 confirm those physiological ones that have been stated by M. 

 Duchenne. I have had occasion to observe that the manner in 

 which the extra current is produced, may give rise to a division 

 of the induced spark, of which the following fact may convey an 

 idea. In experiments upon the rapidity of the transmission of 



