RANGOON oil is not found in this market. It is a variety of naphtha or petroleum found at Rangoon, in Asia, and contains a variable percentage of solid paraffin. Kerosene with a very little paraffin dissolved in it, would undoubtedly answer the same purpose. Good sperm oil or tallow (free from salt) will serve quite as well. It is scarcely necessary to caution the reader that all oily matter should be removed from the knife before it is used for cutting sections. This is best effected by dipping it in hot water and carefully wiping it. NOTE B., Page 15. METHYLATED spirit is alcohol which contains a small percentage of methyl. This renders it unfit for use in the manufacture of liquors or even chloroform, but does not injure it as a preservative fluid. The scientific men of Great Britain have the privilege of obtaining this fluid free from duty, and consequently they make very general use of it. In this country the student of science has no such privilege, and must use the more expensive alcohol. This however is but of a piece with other restrictions placed upon scientific pursuits in this country, where men like Marshall Jewell and Hannibal Hamlin have influence enough to pass laws which prohibit the exchange by mail of microscopic specimens, which pass freely in every other civilized country. True methyl alcohol, or methylated spirits, is not to be had in this country, and therefore whenever this liquid is directed to be used in English books the American microscopist must substitute good alcohol. What is sold for “methyl alcohol” is wood spirit or wood naphtha, and will not serve the purposes of the microscopist, though it answers well enough for spirit lamps, making varnishes, etc. NOTE C., Page 20. THE method described in the text is generally known as the “free-hand” method, and although it is not generally employed for the production of cabinet specimens or slides that are intended for sale, yet it possesses so many advantages that every student should endeavor to acquire the art of cutting sections without the use of the microtome. For purposes of study such sections are quite equal to the best of those usually found on sale, and for the encouragement of beginners we may add that we have seen sections cut by the free-hand method which for size, thinness and accuracy, excelled any that we have ever seen produced with the microtome. Indeed Schäffer distinctly affirms that no microtome can equal the skilled hand in the production of thin sections. NOTE D., Page 22. THE mere existence of a binding screw should be no objection, and where bushings are employed it is sometimes necessary. But as the author well observes, a binding screw cannot be used to secure histological preparations. NOTE E., Page 22.