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PROFESSOR MATTEUCCl’S ELECTRO-PHYSIOLOGICAL RESEARCHES. 
nerve be divided rapidly at the precise point where it enters the muscle, the limb is 
thrown into contraction without its remaining in a state of tetanus. But if, instead 
of this, the nerve be divided higher up near to its issue from the spinal marrow, then 
the tetanic contraction takes place as usual. 
We will next consider the circumstances which modify or destroy this phenomenon. 
None of those frogs which were killed after the administration of large doses of mor- 
phine, so as to manifest every symptom of narcotism, ever exhibited tetanic contrac- 
tions. The same thing occurs with frogs which have been made to support heavy 
weights with their legs. The circumstance which suddenly puts a stop to the tetanic 
contractions is the passage of the inverse current, the same, that is to say, by which 
the phenomenon is produced. Generally two or three seconds after the circle is 
closed again, the limb falls into its natural posture. If, on the other hand, the cur- 
rent merely ceases to pass, it will in general be three minutes before that happens ; 
and the same is the case pretty nearly if the direct current is passed. To obtain 
these phenomena with great precision, care must be taken not to reverse the direction 
of the current upon the same nerve several times successively. 
I was desirous of trying whether the species of tetanic contraction, or rather of 
corpse-like rigidity with which a muscle is seized after a shock from the jar, was dis- 
sipated by the passage of the current, direct or inverse, through its nerve. This is 
not at all the case, and whenever it has occurred, the passage of the current has not 
produced contraction. 
I will here state that, acting with the electric current upon the nerves of living 
warm-blooded animals, as rabbits and dogs, a phenomenon analogous to that which 
we have studied in the frog is very clearly seen to follow the action of the inverse 
current ; only it is observable that in these animals the tetanic contractions last a 
much shorter time, especially if the vitality of the animal is very great ; the same 
fact besides is verified in the frog. 
How is this tetanic action produced ? It is easy to convince oneself, if any doubt 
could be entertained upon the subject, that there is no electricity rendered latent 
either in the nerves or in the muscles by the passage of the inverse current. My 
endeavours to discover signs of any, by the aid of the condenser, have been entirely 
fruitless. Likewise there are no signs on opening the circuit of any electric current 
in circulation. I have made myself quite certain of this fact by means of the galva- 
nometer, employing at the same time a pile of tetanized frogs. 
The phenomenon which we have studied thus at length belongs clearly to the 
nerve, and takes its origin from the relation, the nature of which is yet undetermined, 
which exists between nervous influence and the action of the electric current accord- 
ing to the direction of the latter. 
It has been distinctly proved in the fourth series of these electro-physiological 
researches, that the passage of the direct current destroys the excitability of the 
nerve, and that this is not the case with the inverse current, which acts in a contrary 
