_The Haversack._--In order that the above-mentioned instruments and the various bottles, vials, and boxes which are needed for the preservation of specimens may most conveniently and with the least impediment to the collector be carried along on excursions, a haversack is indispensable. This is made either of leather or, still better, of some waterproof cloth, and should contain various compartments of different sizes; one for stowing away the nets, the sieve, and the larger instruments, and several smaller ones for boxes and vials--the whole so arranged that each desired object can readily be taken out and that nothing will drop out and get lost. The haversack is slung across the shoulders by means of a leather strap, and a full field outfit need not be very heavy nor seriously interfere with free bodily movements. Many of the smaller objects are most conveniently carried in the pockets of the coat, which acquires, therefore, some importance to the collector. The coat should be of some durable stuff and provided with many pockets, so arranged that in stooping nothing falls out of them. _The Lens and Microscope._--In the examination of the minuter forms of insect life the naked eye is not sufficient, and a hand-lens, or, for more delicate work, the compound microscope will be found necessary. I had, in my early experience, some difficulty in getting a satisfactory hand-lens, and the use of a poor hand-lens in time injures the eyesight, as I know by a year's rather disagreeable experience. For a hand-lens the achromatic lenses formerly manufactured by A. K. Eaton, of Brooklyn, N. Y., and now made by John Green, 35 Liverpool street, East Boston, Mass., are most excellent in workmanship and are satisfactory in every respect. A very good lens can also be purchased of any of the leading manufacturers of microscopical apparatus in this country. The kind of compound microscope to be purchased will depend upon the nature of the work of the investigator. Very serviceable instruments are made by J. W. Queen & Co., Philadelphia, Pa., and by the Bausch & Lomb Optical Company, of Rochester, N. Y., and others. The German microscopes are in many respects superior to those of American make, and if one has sufficient means, I would recommend the purchase of one of the better instruments of Zeiss's manufacture, which may be obtained either direct from the manufacturers or through Queen & Co., or from the Boston Educational Supply Company. Microscopic material, including slides, cover glasses, instruments for mounting, mounting media, staining fluids, etc., may be obtained of either of the firms named above. Having thus indicated somewhat fully the general methods of collecting, and the paraphernalia most desirable in collecting, it will be well to go still further into detail, and in connection with the different orders give some more specific information that will be valuable as a guide not only to the general collector, but to the specialist.