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164 current that may be produced by it, without generating currents in the apparatus we employ. The question arises—what contact can be made with a muscle without generating currents at the surface of contact?

After much labour, Professor E. du Bois Reymond of Berlin invented the proper appliances. Let me mention in passing the name of du Bois Reymond with much respect. He has not only laid the foundations, but he has built much of the superstructure of our knowledge of electro-physiology; he, more than most men, has investigated the hidden processes in muscles and nerves, devising and even constructing, in the first instance, with his own hands, much of the apparatus now employed in such investigations; and it is interesting to know that he demonstrated, in 1855, many of his discoveries at a famous lecture given in this Institution. Well, du Bois Reymond found that zinc troughs, carefully rubbed over with mercury, or, as it is termed, amalgamated, and filled with a saturated solution of sulphate of zinc, fulfilled the conditions. Into these troughs we place pads of white blotting-paper (Swedish filter-paper). But if we laid the