In all tropical countries, human beings shew an extraordinary and almost irresistible desire to swallow earth; and not alkaline earths, which they might be supposed to crave to neutralize acid, but unctuous and strong-smelling clays. It is often necessary to confine children to prevent them from running out to eat earth immediately after a fall of rain. I have observed with astonishment the Indian women in the village of Banco on the Magdalena River, whilst engaged in shaping earthen vessels on the potter’s wheel, put great lumps of clay into their mouths. The same thing was remarked at an earlier period by Gili. (Saggio di Storia Americana, T. ii. p. 311.) Wolves also eat earth, and especially clay, in winter. It would be important to examine carefully the excrements of animals and men that eat earth. With the exception of the Otomacs, individuals of all other races who indulge for any length of time the strange desire of earth-eating have their health injured by it. At the mission of San Borja, we saw the child of an Indian woman, who, his mother said, would hardly eat anything but earth. He was, however, wasted nearly to a skeleton. Why is it that in the temperate and cold zones this morbid craving for eating earth is so much more rare, and is almost entirely confined, when it is met with, to children and pregnant women; while in the tropics it would appear to be indigenous in all quarters of the globe? In Guinea the negroes eat a yellowish earth, which they call Caouac. When brought as slaves to the West Indies, they try to obtain a similar earth, and affirm that in their own country the habit never did them any harm. In the American Islands they were made ill by it, and it was forbidden in consequence; but a kind of earth (un tuf rouge jaunâtre) was, in 1751, sold secretly in the market in Martinique. “Les negres de Guinée disent que dans leur pays ils mangent habituellement une certaine terre, dont le goût leur plait, sans en être incommodés. Ceux qui sont dans l’abus de manger du Caouac en sont si friands qu’il n’y a pas de châtiment qui puisse les empêcher de dévorer de la terre.” (Thibault de Chanvalon, Voyage à la Martinique, p. 85.) In the Island of Java, between Sarabaya and Samarang, Labillardière saw small square reddish-coloured cakes exposed for sale in the villages. The natives called them tana ampo (tanah, in Malay and Javanese, signifies earth). On examination and enquiry he found that the cakes consisted of reddish clay, and that they were eaten. (Voyage à la Récherche de la Pérouse, T. ii. p. 322.) The edible clay of Samarang has recently been sent to Berlin by Mohnike, in 1847, in the shape of rolled tubes, like cinnamon, and has been examined by Ehrenberg. It is a fresh-water formation deposited on limestone, and consisting of microscopic Polygastrica, Gaillonella, Naviculas, and Phytolitharia. (Bericht über die Verhandl. der Akad. d. Wiss. zu Berlin, aus dem J. 1848, S.