21 ANNUAL OF SCIENTIFIC DISCOVERY. 



of one common cause. This has proved the first step to still grander 

 abstractions, to that which conceives the induction of all the species of 

 imponderable fluids of the chemistry of our student days, together with 

 gravitation, chemicity, and neuricity, to interchangeable modes of action of 

 one and the same all-pervading life-essence. Galvani arranged the parts of 

 a recently-mutilated frog, so as to bring a nerve in contact with the external 

 surface of a muscle, when a contraction of the muscle ensued. In this sug- 

 gestive experiment, the Italian philosopher, who thereby initiated the induct- 

 ive inquiry into the relation of nerve force to electric force, concluded that 

 the contraction was a necessary consequence of the passage of electricity 

 from one surface to the other by means of the nerve. He supposed that the 

 electricity was secreted by the brain, and transmitted by the nerves to differ- 

 ent parts of the body, the muscles serving as reservoirs of the electricity. 

 Volta made a further step by showing that, under the conditions or arrange- 

 ments of Galvani's experiments, the muscle would contract, whether the 

 electric current had its origin in the animal body, or from a source external 

 to that body. Galvani erred in too exclusive a reference of the electric force 

 producing the contraction to the brain of the animal; Yolta, in excluding 

 the origin of the electric force from the animal body altogether. The deter- 

 mination of " the true " and "the constant" in these recondite phenomena, 

 has been mainly helped on by the persevering and ingenious experimental 

 researches of Mateucci and Du Bois Rcymond. The latter has shown that 

 any point of the surface of a muscle is positive in relation to any point of 

 the divided or transverse section of the same muscle; and that any point of 

 the surface of a nerve is positive in relation to any point of the divided or 

 transverse section of the same nerve. Mr. Baxter, in still more recent re- 

 searches, has deduced important conclusions on the origin of the muscular 

 and nerve currents, as being due to the polarized condition of the nerve or 

 muscular fibre, and the relation of that condition to changes which occur 

 during nutrition. From the present state of neuro-electricity, it may be 

 concluded that nerve force is not identical with electric force, but that it 

 may be another mode of motion of the same common force. It is certainly 

 a polar force, and perhaps the highest form of polar force: 



" A motion which may change, but cannot die; 

 An image of some bright eternity/' 



The present tendency of the higher generalizations of Chemistry seems to 

 be towards a reduction of the number of those bodies which are called 

 "elementary;" it begins to be suspected that certain groups of so-called 

 chemical elements are but modified forms of one another; that such groups 

 as chlorine, iodine, bromine, fluorine, and as sulphur, selenium, phosphorus, 

 boron, may be but allotropic forms of some one element. Organic Chemis- 

 try becomes simplified as it expands; and its growth has of late proceeded, 

 through the labors of Hoffmann, Berthelot, and others, with unexampled 

 rapidity. An important series of alcohols and their derivatives, from amylic 

 alcohol downwards ; as extensive a series of ethers, including those which 

 give their peculiar flavor to our choicest fruits ; the formic, butyric, succinic, 

 lactic, and other acids, together with other important organic bodies, are 

 now capable of artificial formation from their elements, and the old barrier 

 dividing organic from inorganic bodies is broken down. To the power 

 which mankind may ultimately exercise through the light of synthesis, who 



