For the study of the anatomy, or histology, of insect tissues, the laboratory or working room must have a certain minimum of equipment and the student a certain elementary training in histologic method or technic. By the technic of insect histology is meant the particular methods of killing, fixing, hardening, clearing, infiltrating and imbedding, sectioning, staining, and mounting, so that the various body tissues may be available for examination and study under considerable microscopic

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... cation. With the methods of manipulation acquired by instruction and experience, the actual study of the histologic characteristics of the various particular tissues and organs of the insect body can be undertaken. The tissues should be studied first, for almost any organ comprises in its intimate make-up several distinct tissues or kinds of cellular aggregates. In this paper I purpose giving, first, a brief account of a generally applicable course of procedure in preparing insect tissues for histologic study, and then a series of brief directions and hints for the recognition and study of the various typical or normal insect tissues, and finally similar directions and suggestions for the study of the fine anatomy of the principal insect body-organs. As in Studies I (PSYCHE, vo1. 9, P. 207)on insect anatomy and Studies II (Zoo. dr., p. 246) on the development of the histoblasts of wings and legs, the giant crane-fly rolorusia rubiginosa was used for specific subject, the same insect species will be used as principal subject of this paper. But it is plain, that the similar study of any other insect may be based on the study here outlined of this particular one. HISTOLOGIC TECHNIC. 2Villing and flxing.--The chitinized cuticula of the insect body is nearly impervious to fixing fluids, so that for quick killing and fixing of the tissues, heat is, in most cases, the best killing agent. Tissues that have been dissected out from the body of a live (chloroformed) specimen may be fixed without heat in any of the usual fluids. To kill and fix the whole body of insects, drop specimens alive into boiling water; leave them in this but a moment or two, i. e., until the body is rigid, then transfer to 3o% alcohol. While here puncture the body wall with a needle, scalpel, or fine scissors in several places, not cutting deeply nor making the wound in the dorso-ventral median longitudinal plane of the body. Leave in 3o alcohol three hours; then transfer to 5o alcohol for three hours, then to 75 o alcohol for from six to twelve hours, then to 85 alcohol I903] KELLOGG STUDIES :'OR STUDEIVTS