In 1764, however, Dr. Peter Canvane, of Bath, who had practised for seven years in the West Indies, published a treatise entitled “A Dissertation on the Oleum Palmæ Christi, sive Oleum Ricini, or (as it is commonly call’d) Castor Oil,” in which he warmly recommended the oil as a gentle purgative, particularly in cases of “dry belly ache.” His advocacy soon took effect, for in the second edition of his treatise published in 1769, he says it had become officinal, by which he meant was sold in the shops, “at Apothecaries Hall and several other shops in London and Bath.” Dr. Odier, of Geneva, who visited England in 1776, became then acquainted with the medicine, and subsequently brought it to the notice of Continental physicians. It was admitted into the London Pharmacopœia in 1788. The name “Ricinus” was in Latin the name of the parasite known as the dog-tick, _Ixodes ricinus_, and was transferred to the Palma Christi seeds because of their resemblance to the insect. In Greek the same insect was called the kroton, and Theophrastus and Dioscorides describe the Palma Christi seeds as kroton seeds. Curiously the name kroton has been applied in America to the cockroach, not from any association with ticks, but from a belief that the insects came from the Croton River when the water from that source was brought to New York in 1842. The name of castor oil is supposed to have been given to the oil in consequence of a mistaken idea in the Western Indies that the plant which yielded the seeds was _Agnus Castus_. There was, however, a castor oil and compound castor oil in medicinal use in England and other countries until the eighteenth century. The simple oil was made by digesting castorum in oil and boiling it with wine until the latter had all evaporated. The compound oil contained besides a number of aromatic gums and spices. Possibly the taste of the oil from the Palma Christi seeds recalled that from the old oil of castor, and the name may thus have been transferred. CINCHONA. It is not possible to determine from the legends and reports collected by the many competent naturalists who visited Peru in the seventeenth and eighteenth centuries with the special object of investigating the history of the cinchona trees whether it was known or used as a medicine by the natives before its virtues were ascertained by Europeans.