I have described the capture of the Gymnoti in detail in another place. (Observations de Zoologie et d’Anatomie comparée, vol. i. p. 83–87; and Relation historique, T. ii. p. 173–190). M. Gay Lussac and I found the experiment without a circuit succeed perfectly with a living Gymnotus, which was still very vigorous when brought to Paris. The discharge is solely dependent on the will of the animal. We did not see any spark, but other physicists have done so on several occasions.
[43] p. 23.—“Awakened by the contact of moist dissimilar particles.”
In all parts of organic bodies dissimilar substances are in contact with each other: in all, solids are associated with fluids. Thus, wherever there is organization and life, there is also electric tension or the play of the voltaic pile, as the experiments of Nobili and Matteucci, and especially the latest admirable labours of Emil du Bois, teach us. The last named physicist has succeeded in “manifesting the presence of the electric muscular current in living and wholly uninjured animal bodies:” he shews that “the human body, through the medium of a copper wire, can cause a magnetic needle at a distance to be deflected at pleasure, first in one and then in the opposite direction.” (Untersuchungen über thierische Elektricität, von Emil du Bois-Reymond, 1848, Bd. i. S. xv.) I have witnessed these movements produced at pleasure, and have had the gratification of seeing thereby great and unexpected light thrown on phenomena to which I had laboriously and hopefully devoted several years of my youth.
[44] p. 23.—“Osiris and Typhon.”
On the conflict between two races of men, the Arabian pastoral people in Lower Egypt, and the agricultural race in Upper Egypt who were in a more advanced state of civilisation, on the fair-haired Prince Baby or Typhon, who founded Pelusium, and on the dark-complexioned Dionysos or Osiris, see Zoëga’s ancient, and now for the most part abandoned views, in his great work “De Origine et Usu Obeliscorum,” p. 577.
[45] p. 24.—“The boundary of a partial European cultivation.”
In the Capitania general de Caracas, as generally every where on the eastern shores of America, the cultivation introduced by Europeans, and their presence and influence, are limited to a narrow strip of country along the coast. In Mexico, New Granada, and Quito, on the other hand, European civilisation has penetrated deep into the interior of the country, and advanced up the ridges of the Cordilleras. There existed in these last-named regions a considerable degree of settled and civilised life previous to the arrival of the Spaniards; and they have followed this civilisation wherever they found it, regardless whether its seat was near or at a distance from the sea coast. They retained and enlarged the ancient cities, of which they either mutilated the old significant Indian names, or gave them new names, as, for example, of Christian saints.
[46] p. 24.—“Massive leaden-coloured granite rocks.”
In the Orinoco, and more especially at the Cataracts of Maypures and Atures, all blocks of granite, and even white pieces of quartz, whenever they are touched by the water of the river, acquire a greyish-black coating which scarcely penetrates a hundredth of a line below the surface of the rock. The appearance produced is that of basalt, or fossils coloured with graphite. The crust appears to contain manganese and carbon; I say appears, for the phenomenon has not yet been thoroughly examined. Something similar was remarked by Rozier on the syenite rocks of the Nile, near Syene and Philæ; by the unfortunate Captain Tuckey on the rocky banks of the Congo; and by Sir Robert Schomburgh on the Berbice. (Reisen in Guiana und am Orinoko, S. 212.) On the Orinoco these leaden-coloured rocks are considered to give out pernicious exhalations when wet; and their proximity is believed to produce fevers. (Rel. hist. T. ii. p. 299–304.) In the Rio Negro, and generally in the South American rivers which have “black waters,” “aguas negras,” or waters of a coffee-brown or yellow tint, no such effects take place. No black colour is imparted to the granite rocks by the waters; that is to say, they do not act upon the stone so as to form from its constituent particles a black or leaden-coloured crust.
[47] p. 24.—“The rain-announcing howlings of the bearded apes.”