Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

we may fairly conclude that in such a case lead is not the cause of the attack. The electric current is here the only reliable diagnostic test. (See p. 478, Note C, and Appendix.) Dr. Duchenne admits, it is true, that the deeper strata of muscles, which are covered by the superficial muscles, will not exhibit electro-muscular contraction from direct Faradaization ; but as atrophy diminishes the superficial muscles earliest- and mostly, he has been thus helped to the knowledge of the physio- logical function of every muscle in the living body. I may mention, in this connection, as one of the most remarkable facts quoted by recent writers, viz., it is found that the mus- cle extensor communis digitorum has no influence whatever on the extension of the second and third phalanges, as generally thought, but only on the first ; that it is in fact the small interossei that extend the second and third phalanges, while the lumbricales bend the first phalanx ; that the flexor sublimis and profundus muscles bend the second and third phalanges, but not the first. Pathological facts have also demonstrated this, as in cases of lead palsy and muscular atrophy. We find in cases of lead palsy that the extensor digitorum situated on the back of the forearm is palsied, and perhaps atrophied also; but the affection does not reach the lumbricales and interossei. In lead palsy, therefore, the capability of extending the seijpnd and third phalanges remains normal; it is only the first set of phalanges that cannot be extended, and this gives the character- istic " dropped hand." On the contrary, if there is paralysis, and perhaps atrophy too, of the interossei and lumbricales, while the extensor digitorum is not at all paralyzed, as in " wasting palsy," or after some severe sickness, then the fingers present the appearance of claivs; the hand is extremely lean, and the interosseous spaces are deeply hollowed out. Here we see the first phalanges can be extended and contracted at will; but the second and third phalanges are constantly bent. This is the reverse of what takes place in lead-palsy, and is a diag- nostic sign between wasting-palsy and lead-palsy.